Luminous Landscape Forum

Raw & Post Processing, Printing => Digital Image Processing => Topic started by: st326 on March 29, 2007, 08:39:48 pm

Title: Synthetic HDR
Post by: st326 on March 29, 2007, 08:39:48 pm
Hi all,

I have been doing a bit of experimentation with HDR recently, and had an idea about synthesizing extra dynamic range (particularly in shadow areas) from a single image rather than a bracketed sequence of images.

I've written it up here:

Synthetic HDR at findatlantis.com (http://findatlantis.com/wiki/index.php/Synthetic_HDR)

in some detail, but to cut a long story short, it works by using convolution to simulate binning, then generating a series of simulated greater exposures (that are guaranteed not to introduce any quantisation effects), then doing a standard HDR merge and tone mapping of the resulting image. The initial results are encouraging -- I'll include an example here, but there's more detail on my web site.

Here's the original test image:

(http://findatlantis.com/wiki/images/1/12/Lj-Base-image.jpg)

Base image

It was shot with a Bronica ETRS, 100mm macro on an auto bellows, Megavision E4 Monochrome back (16 megapixel, 4096x4096, 12-bit).

(http://findatlantis.com/wiki/images/0/0c/Lj-Synthetic-hdr-version.jpg)

Synthetic HDR image

This is an effectively 20-bit synthetic HDR version of the same image (no other images were used), tone mapped back to 8 bits for web purposes.

For comparison, here's a 'real' HDR image made the conventional way by doing a Photoshop HDR merge on a series of 7 separate exposures, 1 stop apart:

(http://findatlantis.com/wiki/images/6/64/Lj-Real-hdr-32bit.jpg)

Real HDR image

There's not much to choose between the two, really -- most of the difference is down to different tone mapping settings, which could probably be overcome with a bit of dodging and burning.

Rather more telling is comparing (slightly out-of-focus) 100% crops from the bottom right hand corner:

(http://findatlantis.com/wiki/images/b/bc/Lj-Bottomrightoriginalautolevels.jpg)

Original image, 100% crop, auto-levels applied

This is the original image, cropped and adjusted with Levels. Compare this with the same area of the synthetic HDR image:

(http://findatlantis.com/wiki/images/3/39/Lj-Bottomrightsynhdrautolevels.jpg)

There's surprisingly little to choose between the two in terms of perceived resolution, but in the synthetic HDR version there is no sign of the horrible pixellation or posterisation, just something looking not unlike film grain. In this example there are some slight artifacts from my having used rectangular convolution kernels, but this could easily be avoided by using circular kernels instead.

I don't think this technique can necessarily replace HDR, but it does appear to be able to regain shadow detail in single frames surprisingly well. I'm considering implementing this algorithm as a Photoshop plugin, but in the mean time, the web page I linked above tells you enough to be able to reproduce my results.
Title: Synthetic HDR
Post by: laughingbear on March 29, 2007, 09:28:49 pm
Quote
Here comes the big idea: perhaps we could simulate different exposures with binning, then use established HDR techniques to recombine them into a final image, such that the inevitable loss of resolution is just confined to shadow areas?

Hello Sarah,

Wow, it appears as if you are onto something there, most impressive!

I was just thinking about this "limitation" of shooting exposure brackets as base material for HDR landscapes. I mean, nice cloud patterns on a perfectly windstill day work fine, but how often do we find that?

Thanks a lot for sharing your findings. A photoshop plugin would sure be a very handy solution.

Best whishes
~^..^~
Bear
Title: Synthetic HDR
Post by: st326 on March 29, 2007, 10:32:12 pm
Quote
Hello Sarah,

Wow, it appears as if you are onto something there, most impressive!

I was just thinking about this "limitation" of shooting exposure brackets as base material for HDR landscapes. I mean, nice cloud patterns on a perfectly windstill day work fine, but how often do we find that?

Thanks a lot for sharing your findings. A photoshop plugin would sure be a very handy solution.

Best whishes
~^..^~
Bear
[a href=\"index.php?act=findpost&pid=109514\"][{POST_SNAPBACK}][/a]

I think a PS plugin could potentially do a much better job, without any of the artifacts associated with the HDR merge or tone mapping, because I can figure out all of the maths to get exact solutions. My ideal would be something like, put PS into 16-bit mode (if it isn't already), then have the plugin synthesize any missing low-order precision, whilst keeping the image bit-for-bit exactly the same as the original except for shadow data. This should mean that you'd get essentially no artifacts whatsoever, just much more (cleaner) shadow information to play with in dodging and burning. It's a little different in philosophy to traditional HDR, I suppose, but I can see this being really good for dealing with printing difficult images. I'm not so concerned with getting into the more stylised (dare I say it a bit cliched?) applications of HDR -- my thing is fine art photography, and my motivation for this is trying to make better prints (better performances of the score, to misquote Ansel Adams), if you see what I mean.
Title: Synthetic HDR
Post by: BernardLanguillier on March 29, 2007, 10:40:47 pm
Is it just me, or do both real HDR and simulated HDR images show very large areas of completely burned highlights?

Shadow detail is important, but IMHO HDR should focus on preserving the highlights while keeping some details in the shadows.

What I see as a problem with the current samples is probably just a matter of choice when mapping back from high bit to 8 bits, but I would personnaly find the current images unusable.

Regards,
Bernard
Title: Synthetic HDR
Post by: st326 on March 29, 2007, 10:58:13 pm
Quote
Is it just me, or do both real HDR and simulated HDR images show very large areas of completely burned highlights?

Shadow detail is important, but IMHO HDR should focus on preserving the highlights while keeping some details in the shadows.

What I see as a problem with the current samples is probably just a matter of choice when mapping back from high bit to 8 bits, but I would personnaly find the current images unusable.

Regards,
Bernard
[a href=\"index.php?act=findpost&pid=109520\"][{POST_SNAPBACK}][/a]

I'm not so keen on that either, but I was concentrating on shadow detail here. I'm not that convinced of how good Photoshop's Merge-to-HDR feature actually is, to be honest -- one of the reasons I want to implement this as a plugin is that I could bypass that entirely. This article is really a proof-of-concept based on simulating the concept with manual Photoshop-prodding rather than anything definitive. With a plugin, it should be possible to keep the most-significant bits of the brightness information bit-for-bit identical to the original image, and just synthesize extra bits within shadow areas. As for tonality, it would then just basically be up to you to do your thing with levels and curves as normal -- the technique itself wouldn't affect that in any way. It should be very fast, too, because it won't need to do any significant maths outside shadow areas.

Also -- an important caveat: none of these images are intended to be great art. It's just that they happened to have the right kinds of properties, and it happened to be the only image sequence across a full 7 stops that I had to hand for comparison. Where I think great art *could* come out of this is in coaxing more and better shadow detail out of difficult images in printing -- my gut feeling is that a plugin could be a godsend for this. It's also potentially the kind of thing that you could build into a camera's onboard DSP firmware.
Title: Synthetic HDR
Post by: Ray on March 29, 2007, 11:12:31 pm
Good point, Bernard. There appears to be a few specral blown highlights in the original and one larger than specral blown highlight.

All of these seem to have been significantly enlarged in both the synthetic and real HDR images.
Title: Synthetic HDR
Post by: st326 on March 29, 2007, 11:14:04 pm
Quote
Good point, Bernard. There appears to be a few specral blown highlights in the original and one larger than specral blown highlight.

All of these seem to have been significantly enlarged in both the synthetic and real HDR images.
[a href=\"index.php?act=findpost&pid=109526\"][{POST_SNAPBACK}][/a]

As I mentioned previously, this is really due to Photoshop's crappy HDR merge. The plugin won't have this problem, if for no other reason that it'll only actually affect shadow areas anyway.
Title: Synthetic HDR
Post by: Tom.D.Arch on March 30, 2007, 12:57:09 am
Quote
<clip> ...  then have the plugin synthesize any missing low-order precision, whilst keeping the image bit-for-bit exactly the same as the original except for shadow data. This should mean that you'd get essentially no artifacts whatsoever, just much more (cleaner) shadow information to play with in dodging and burning. <clip>
[a href=\"index.php?act=findpost&pid=109519\"][{POST_SNAPBACK}][/a]

Visually, your example looks great - no amazing.  Somehow, though, you should be running up against some law of 'information theory'.  Either the information is there in the original capture, or it isn't.  In theory you shouldn't be able to "synthesize any missing low-order precision", particularly in comparison with 'normal' HDR merge, where there really is more information to draw from.  Nonetheless, the proof seems to be in the pudding - this is really interesting!
Title: Synthetic HDR
Post by: st326 on March 30, 2007, 01:35:54 am
Quote
Visually, your example looks great - no amazing.  Somehow, though, you should be running up against some law of 'information theory'.  Either the information is there in the original capture, or it isn't.  In theory you shouldn't be able to "synthesize any missing low-order precision", particularly in comparison with 'normal' HDR merge, where there really is more information to draw from.  Nonetheless, the proof seems to be in the pudding - this is really interesting!
[a href=\"index.php?act=findpost&pid=109538\"][{POST_SNAPBACK}][/a]

There's no violation of information theory here. I'm not peddling perpetual motion. ;-) There's simply a tradeoff between resolution and bit depth -- normally, this would result in a poor quality image, but by restricting the effect to deep shadow areas, there should be no visible degradation to brighter parts of the image, whilst retaining more shadow detail due to the greater dynamic range. It's not inventing any information -- just kind-of spreading it out in a way that looks better to human visual perception, if that makes any sense.
Title: Synthetic HDR
Post by: Ray on March 30, 2007, 01:44:29 am
Quote
Either the information is there in the original capture, or it isn't.  In theory you shouldn't be able to "synthesize any missing low-order precision", particularly in comparison with 'normal' HDR merge, where there really is more information to draw from.  [a href=\"index.php?act=findpost&pid=109538\"][{POST_SNAPBACK}][/a]

That's my view also. There are many ways to skin a cat. This is obviously one of them, but we need more variations of the pudding, using different processing techniques, to determine if any ultimate advantage has been acheived.
Title: Synthetic HDR
Post by: st326 on March 30, 2007, 02:05:43 am
Quote
That's my view also. There are many ways to skin a cat. This is obviously one of them, but we need more variations of the pudding, using different processing techniques, to determine if any ultimate advantage has been acheived.
[a href=\"index.php?act=findpost&pid=109545\"][{POST_SNAPBACK}][/a]

It's not opinion on my part, it's mathematics.

I'm not particularly surprised that some people here reacted negatively to the idea -- having lurked here for quite a while now, it seems to be pretty much par for the course. Nevertheless, I will go ahead and write the plugin. I intend to give it away for free, so people can use it or not, it's entirely up to them.

"Don't worry about people stealing an idea. If it's original, you will have to ram it down their throats." -- Howard Aiken
Title: Synthetic HDR
Post by: Ray on March 30, 2007, 02:23:29 am
Quote
It's not opinion on my part, it's mathematics.

I'm not particularly surprised that some people here reacted negatively to the idea -- having lurked here for quite a while now, it seems to be pretty much par for the course. Nevertheless, I will go ahead and write the plugin. I intend to give it away for free, so people can use it or not, it's entirely up to them.

"Don't worry about people stealing an idea. If it's original, you will have to ram it down their throats." -- Howard Aiken
[a href=\"index.php?act=findpost&pid=109548\"][{POST_SNAPBACK}][/a]

Is your name really Sarah? Do a full job on any particular image of your choice. Send me the RAW file via PM, but not too large a RAW file, and let's compare your synthetic HDR with my photoshopped version. Okay?
Title: Synthetic HDR
Post by: Ray on March 30, 2007, 02:29:22 am
Better still. Make the RAW image available to everyone through a link, so we can all give your theory a good test and comparison.
Title: Synthetic HDR
Post by: st326 on March 30, 2007, 02:33:25 am
Quote
Is your name really Sarah? Do a full job on any particular image of your choice. Send me the RAW file via PM, but not too large a RAW file, and let's compare your synthetic HDR with my photoshopped version. Okay?
[a href=\"index.php?act=findpost&pid=109550\"][{POST_SNAPBACK}][/a]

As it stands, I don't think an approach based on Photoshop's HDR merge is worth doing any serious comparisons with -- I'm not really happy with its results. Its results seem a bit off somehow -- I think it is including too much signal from the higher exposure frames, which is what's washing out the highlights. It happens on traditional HDR images too, it's not just mine. It's enough to demonstrate proof of concept, but that's all, which is why I intend to release a plugin that implements the algorithm optimally. Once that's available, you are welcome to compare it however you like.

And, to the rest of your question, yes, my name is Sarah, by day job I'm a rocket scientist (yes, really) at NASA Ames. I have a Cambridge PhD in space electronics, and a couple of decades experience in software engineering and electronic design, including a fair bit of signal processing, so I'm not just making this stuff up!
Title: Synthetic HDR
Post by: st326 on March 30, 2007, 02:41:30 am
Quote
Better still. Make the RAW image available to everyone through a link, so we can all give your theory a good test and comparison.
[a href=\"index.php?act=findpost&pid=109551\"][{POST_SNAPBACK}][/a]

I'm uploading it, and a full res version of the result I got. It'll take a while (the files aren't small), so I'll post links once they are up there.
Title: Synthetic HDR
Post by: Ray on March 30, 2007, 02:41:47 am
Quote
As it stands, I don't think an approach based on Photoshop's HDR merge is worth doing any serious comparisons with -- I'm not really happy with its results. Its results seem a bit off somehow -- I think it is including too much signal from the higher exposure frames, which is what's washing out the highlights. It happens on traditional HDR images too, it's not just mine. It's enough to demonstrate proof of concept, but that's all, which is why I intend to release a plugin that implements the algorithm optimally. Once that's available, you are welcome to compare it however you like.

And, to the rest of your question, yes, my name is Sarah, by day job I'm a rocket scientist (yes, really) at NASA Ames. I have a Cambridge PhD in space electronics, and a couple of decades experience in software engineering and electronic design, including a fair bit of signal processing, so I'm not just making this stuff up!
[a href=\"index.php?act=findpost&pid=109553\"][{POST_SNAPBACK}][/a]

I'm impressed (are you still single? - okay ignore that if you wish). What you are saying is, at this point in time you don't have more than a substandard prototype image. If that's the case, we can't really comment further, can we?
Title: Synthetic HDR
Post by: Ray on March 30, 2007, 02:50:38 am
Quote
I'm uploading it, and a full res version of the result I got. It'll take a while (the files aren't small), so I'll post links once they are up there.
[a href=\"index.php?act=findpost&pid=109559\"][{POST_SNAPBACK}][/a]

Okay! Thanks! I Look forward to it.
Title: Synthetic HDR
Post by: kal on March 30, 2007, 03:05:58 am
Quote
There's no violation of information theory here. I'm not peddling perpetual motion. ;-) There's simply a tradeoff between resolution and bit depth -- normally, this would result in a poor quality image, but by restricting the effect to deep shadow areas, there should be no visible degradation to brighter parts of the image, whilst retaining more shadow detail due to the greater dynamic range. It's not inventing any information -- just kind-of spreading it out in a way that looks better to human visual perception, if that makes any sense.
[a href=\"index.php?act=findpost&pid=109540\"][{POST_SNAPBACK}][/a]

This makes a lot of sense. In fact it is quite similar to what some point-and-shoot cameras do when they offer iso 1600 or higher, but only at reduced resolution. You are doing the same thing, but selectively on dark areas.

The only real problem I see here is that this approach will work when the interesting part of the image is "correctly" exposed, and you only need to bring out some detail from possibly out-of-focus shadows. If the interesting part of the image is in the shadows, we are going to have a much harder time, since as you said we are trading resolution for bit depth.

Great work anyway, I wish I had thought it before!
Title: Synthetic HDR
Post by: st326 on March 30, 2007, 03:41:59 am
OK, here are the links to the files (warning, moderately big!)

http://findatlantis.com/base-image.tif (http://findatlantis.com/base-image.tif)

http://findatlantis.com/tonemapped16bitversion.psd (http://findatlantis.com/tonemapped16bitversion.psd)

I uploaded a 16-bit TIFF for the source image, partly because that's the exact same image I started with when I was doing the synthetic HDR experiments, and partly because most third-party software makes a mess of decoding monochrome DNG files (this is the Megavision's native format, but Adobe's own DNG decoder insists on trying to decode them as colour images (it tries to interpolate for a Bayer matrix that actually isn't there), so you lose quality and gain weirdness unless you process them with Megavision's software).
Title: Synthetic HDR
Post by: st326 on March 30, 2007, 03:43:58 am
Quote
This makes a lot of sense. In fact it is quite similar to what some point-and-shoot cameras do when they offer iso 1600 or higher, but only at reduced resolution. You are doing the same thing, but selectively on dark areas.

The only real problem I see here is that this approach will work when the interesting part of the image is "correctly" exposed, and you only need to bring out some detail from possibly out-of-focus shadows. If the interesting part of the image is in the shadows, we are going to have a much harder time, since as you said we are trading resolution for bit depth.

Great work anyway, I wish I had thought it before!
[a href=\"index.php?act=findpost&pid=109564\"][{POST_SNAPBACK}][/a]

Thanks. :-)

I'm not expecting this to be something you'd necessarily use on every image, but for the ones where it is relevant (i.e. where you want to pull out a bit more shadow detail and normal dodging and burning or contrast manipulation is giving you too much noise, posterisation and/or Mach banding) I think it will probably be pretty useful.
Title: Synthetic HDR
Post by: kal on March 30, 2007, 03:49:33 am
Quote
There's no violation of information theory here. I'm not peddling perpetual motion. ;-) There's simply a tradeoff between resolution and bit depth -- normally, this would result in a poor quality image, but by restricting the effect to deep shadow areas, there should be no visible degradation to brighter parts of the image, whilst retaining more shadow detail due to the greater dynamic range. It's not inventing any information -- just kind-of spreading it out in a way that looks better to human visual perception, if that makes any sense.
[a href=\"index.php?act=findpost&pid=109540\"][{POST_SNAPBACK}][/a]

Some more thoughts:

- did you try using different convolution kernels?

- in your wiki you compared synthetic HDR with Levels; did you compare it with Levels + low pass filtering applied to (previously) dark areas?
Title: Synthetic HDR
Post by: laughingbear on March 30, 2007, 07:38:06 am
Quote
It's a little different in philosophy to traditional HDR, I suppose, but I can see this being really good for dealing with printing difficult images. I'm not so concerned with getting into the more stylised (dare I say it a bit cliched?) applications of HDR -- my thing is fine art photography, and my motivation for this is trying to make better prints (better performances of the score, to misquote Ansel Adams), if you see what I mean.

I am no scientist by any means, I am musician, but yes, I can see what you mean! This was my spontaneous thought as well, as I am much more interested in print results than anything else.

Your in depth knoweldge and the way you tackle that challenge speaks for itself!

I regret that I can not contribute on a technical level, may be just one thougt, you mention Photoshops HDR function, I would like to think that "Photomatix" http://www.hdrsoft.com/ (http://www.hdrsoft.com/) offers a higher standard for reasons of comparison.

Quote
Nevertheless, I will go ahead and write the plugin. I intend to give it away for free, so people can use it or not, it's entirely up to them.

Wow. This is a very generous touch in deed.

You appear to be one of those people with 72 hours days instead of 24.  
Title: Synthetic HDR
Post by: John Sheehy on March 30, 2007, 08:47:19 am
Quote
I think a PS plugin could potentially do a much better job, without any of the artifacts associated with the HDR merge or tone mapping, because I can figure out all of the maths to get exact solutions. My ideal would be something like, put PS into 16-bit mode (if it isn't already), then have the plugin synthesize any missing low-order precision, whilst keeping the image bit-for-bit exactly the same as the original except for shadow data. This should mean that you'd get essentially no artifacts whatsoever, just much more (cleaner) shadow information to play with in dodging and burning. It's a little different in philosophy to traditional HDR, I suppose, but I can see this being really good for dealing with printing difficult images. I'm not so concerned with getting into the more stylised (dare I say it a bit cliched?) applications of HDR -- my thing is fine art photography, and my motivation for this is trying to make better prints (better performances of the score, to misquote Ansel Adams), if you see what I mean.
[a href=\"index.php?act=findpost&pid=109519\"][{POST_SNAPBACK}][/a]

I've had an idea for something like this for a while, but I haven't gotten around to writing it.  Basically, a filter would simply average local pixels, with a radius proportional to the darkness of the pixel (or the average of its neighbors).  Then you could dodge and burn, as you suggest, or use something like the shadow/highlight tool in PS to bring out the shadows.  For a greyscale camera, the same routine could be used as one that works on RGB color images, but for RAW CFA data, it would probably best be done before demosaicing, while noise is still in one pixel.  I've made a simple FilterMeister filter that does a median effect, but based on the ratio of a pixel to its surroundings, rather than the difference, which has the most effect in shadows, especially for hot pixels; that would be a good pre-processing before reducung the frequency limit of the shadows.

Maybe I'll try my hand at it in FilterMeister this weekend.
Title: Synthetic HDR
Post by: John Sheehy on March 30, 2007, 08:56:39 am
Quote
I uploaded a 16-bit TIFF for the source image, partly because that's the exact same image I started with when I was doing the synthetic HDR experiments, and partly because most third-party software makes a mess of decoding monochrome DNG files (this is the Megavision's native format, but Adobe's own DNG decoder insists on trying to decode them as colour images (it tries to interpolate for a Bayer matrix that actually isn't there), so you lose quality and gain weirdness unless you process them with Megavision's software).
[a href=\"index.php?act=findpost&pid=109569\"][{POST_SNAPBACK}][/a]

You really don't need the services of a RAW converter for a greyscale camera, if you have access to an uncompressed DNG.  You can load uncompressed DNGs into photoshop literally with "load as" and ".raw", and supply the correct parameters in the dialogue.  You can blackpoint the image if not done already in the RAW file, and then use "Levels" for gamma-adjustment.

If DCRAW supports your digital back, then all you need to do is use the "-D" option to get the literal RAW data into PSD format (with the parameter for 16-bit PSD).
Title: Synthetic HDR
Post by: st326 on March 30, 2007, 08:56:50 am
Quote
I am no scientist by any means, I am musician, but yes, I can see what you mean! This was my spontaneous thought as well, as I am much more interested in print results than anything else.

Your in depth knoweldge and the way you tackle that challenge speaks for itself!

I regret that I can not contribute on a technical level, may be just one thougt, you mention Photoshops HDR function, I would like to think that "Photomatix" http://www.hdrsoft.com/ (http://www.hdrsoft.com/) offers a higher standard for reasons of comparison.
Wow. This is a very generous touch in deed.

You appear to be one of those people with 72 hours days instead of 24. 
[a href=\"index.php?act=findpost&pid=109596\"][{POST_SNAPBACK}][/a]

As I've said, I'm not that impressed with Photoshop's merge to HDR function. The best way to do this is to actually solve the equations and come up with an exact solution -- I'll have a go at it over the weekend and see what comes out.
Title: Synthetic HDR
Post by: st326 on March 30, 2007, 08:59:10 am
Quote
You really don't need the services of a RAW converter for a greyscale camera, if you have access to an uncompressed DNG.  You can load uncompressed DNGs into photoshop literally with "load as" and ".raw", and supply the correct parameters in the dialogue.  You can blackpoint the image if not done already in the RAW file, and then use "Levels" for gamma-adjustment.

If CRAW supports your digital back, then all you need to do is use the "-D" option to get the literal RAW data into PSD format (with the parameter for 16-bit PSD).
[a href=\"index.php?act=findpost&pid=109605\"][{POST_SNAPBACK}][/a]

Adobe's RAW support stuffs up Megavision images, unfortunately. Superficially, it will read the files, but it tries to interpolate them as if they had a Bayer matrix, which they don't, so you end up with a loss of resolution and some weird colour artifacts.
Title: Synthetic HDR
Post by: st326 on March 30, 2007, 04:34:53 pm
Quote
Adobe's RAW support stuffs up Megavision images, unfortunately. Superficially, it will read the files, but it tries to interpolate them as if they had a Bayer matrix, which they don't, so you end up with a loss of resolution and some weird colour artifacts.
[a href=\"index.php?act=findpost&pid=109608\"][{POST_SNAPBACK}][/a]

Hmm... I just had another go at it. Seemingly it now works -- it's likely that Adobe have fixed something in one of their recent updates. This is definitely good, because I rather like ACR in comparison with the Megavision software. I'll give it a try again.
Title: Synthetic HDR
Post by: Tim Gray on March 30, 2007, 06:39:38 pm
I used to do blends from a single exposure, but haven't since I started to use the parametric controls in Lightroom.

If I use something like:

Exposure 0
Recovery 0
Fill light 21
Black 0
Brightness 104

Highlights -100
Lights +70
Darks +82
Shadows +100

I seem to get someting that looks a lot like the HDR image (blown highlights included) or am I not pixel peeping sufficiently?  In this case I could blend multiple images using the CTRL ALT ~ method and not increase the blown pixels.

The point is that there appears to be very few 0,0,0 pixels in the shadows so it't not surprising that a fair amount of detail can be recovered given the bit depth of the image.
Title: Synthetic HDR
Post by: Monito on March 30, 2007, 07:08:30 pm
Quote
As I've said, I'm not that impressed with Photoshop's merge to HDR function.[a href=\"index.php?act=findpost&pid=109606\"][{POST_SNAPBACK}][/a]
You can't make a good HDR without good source images.  I followed the link to your writeup.  I'm sorry to say, but your source images aren't a good set for shadow detail.  You have taken too many that are too dark and not enough with increased exposure for shadow detail.
Title: Synthetic HDR
Post by: Monito on March 30, 2007, 07:18:45 pm
You encountered a memory problem merging 7 images twelve bit, 16 MPixel on a 4 GB machine.  Have you set your Photoshop to cross the 1.5 GB Photoshop memory limit?  I don't have the details on how to do it, since I've not had the memory to do it.

I have merged 9 images that are 16 bit TIFF files, 12 MPixel each (4368 x 2912) on the 1.5 GB machine without difficulty.  That's nine files, 75 MB each, producing a 131 MB PSD file, which after some workups became a 303 MB PSD file.  Not too different from the merge you attempted.  Photoshop CS2.
Title: Synthetic HDR
Post by: st326 on March 30, 2007, 07:20:16 pm
Quote
You can't make a good HDR without good source images.  I followed the link to your writeup.  I'm sorry to say, but your source images aren't a good set for shadow detail.  You have taken too many that are too dark and not enough with increased exposure for shadow detail.
[a href=\"index.php?act=findpost&pid=109753\"][{POST_SNAPBACK}][/a]

Possibly so, but the point of the article was actually recovering shadow detail from images that *don't* already conventionally have sufficient shadow detail. The traditional HDR image was given as a comparison really.
Title: Synthetic HDR
Post by: st326 on March 30, 2007, 07:29:11 pm
Quote
You encountered a memory problem merging 7 images twelve bit, 16 MPixel on a 4 GB machine.  Have you set your Photoshop to cross the 1.5 GB Photoshop memory limit?  I don't have the details on how to do it, since I've not had the memory to do it.

I have merged 9 images that are 16 bit TIFF files, 12 MPixel each (4368 x 2912) on the 1.5 GB machine without difficulty.  That's nine files, 75 MB each, producing a 131 MB PSD file, which after some workups became a 303 MB PSD file.  Not too different from the merge you attempted.  Photoshop CS2.
[a href=\"index.php?act=findpost&pid=109755\"][{POST_SNAPBACK}][/a]

Yes, Photoshop keeled over with a crash when I tried it. I didn't realise it had a 1.5GB limit -- I'll look into that. I specifically built this machine for dealing with large images, not so much for the 32MB files from the Megavision, more the 300MB images from the Better Light scan back I use. I quite frequently end up working on 1GB+ photoshop files -- it doesn't take much when the base image is that big by the time you create a couple of adjustment layers.

I was a bit surprised at the crash, to be honest. I wasn't expecting to have a problem with that many images. In one previous project I shot about 70 frames (again with the Megavision back) of the same street scene, then composited them. I'm pretty sure I managed to composite about 30 or so frames at a time, then I did another comp-of-comps to get the final image. I did choose to use 8 bit images, however, because the originals had plenty of contrast anyway and didn't need much in the way of adjustment, but even so, keeling over with just 7 16-bit monochrome 4k x 4k images wasn't impressive.
Title: Synthetic HDR
Post by: Monito on March 30, 2007, 09:02:16 pm
I read the article, st326.  A very interesting use of convolution.  You trade away resolution to get greater bit depth.

I wonder if kind of the opposite could be done.  Astronomers use image stacking for noise reduction which one might loosely say is using multiple images to get better resolution in the luminance (and color) space with the same dynamic range.  The better resolution is important only in the blacks where noise is relatively large.  So it is a noise reduction system.

I wonder if one could use stacking of images to obtain a higher resolution picture of a scene.  It might involve shifting the camera ever so slightly between shots to increase the variation so that each ray is not going through exactly the same bit of glass or dust.  Perhaps lightly tapping the tripod might be enough.

So instead of doing using perhaps four 10 MPixel images taken with an 85mm lens in a 2 x 2 pano to make a 32 MPixel image (some lost due to overlap for stitching), one could make four 10 MPixel images using a 50mm lens and stack them for higher resolution, perhaps approaching 40 MPixel.

I think in principle it could be done. One way might be to super-impose the four images to align the layers (if there has been camera movement; might not be necessary to shift the camera).  From each pixel, create a 2x2 area in the super-image. For each 2x2 area, take one pixel from each of the four layers to fill out the 2x2 area.

The process I have outlined seems naive and I'd have to think about the math a bit, since there might be a more refined solution.  It seems naive, since the assignment to individual cells of the 2x2 areas seems arbitrary.
Title: Synthetic HDR
Post by: John Sheehy on March 30, 2007, 10:28:12 pm
Quote
Adobe's RAW support stuffs up Megavision images, unfortunately. Superficially, it will read the files, but it tries to interpolate them as if they had a Bayer matrix, which they don't, so you end up with a loss of resolution and some weird colour artifacts.
[a href=\"index.php?act=findpost&pid=109608\"][{POST_SNAPBACK}][/a]

I'm not talking about RAW converters at all; you don't need RAW conversion for greyscale.  RAW converters do all sorts of color magic; greyscale RAW is pretty much ready to go, except that black may not be zero, depending on the camera or back, and gamma may not be applied.  IOW, you can do everything a converter would do by simply loading the raw RAW image, and using the Levels tool.

It doesn't matter whether the DNG converter thinks the image is color or greyscale.  Just because a converter interprets the DNG as CFA, doesn't necessarily mean that the DNG file itself has a demosaiced image in it.  DNG stores greyscale and CFA in the same format; only the tags should be different.  If you convert the DNG to uncompressed DNG (if it isn't already), you can rip the grey RAW bitmap right out of it in the "photoshop .raw" dialogue.  It sits in literal english-writing order, right after the header, up to the end of the file, usually.
Title: Synthetic HDR
Post by: st326 on March 30, 2007, 10:45:29 pm
Quote
I read the article, st326.  A very interesting use of convolution.  You trade away resolution to get greater bit depth.

I wonder if kind of the opposite could be done.  Astronomers use image stacking for noise reduction which one might loosely say is using multiple images to get better resolution in the luminance (and color) space with the same dynamic range.  The better resolution is important only in the blacks where noise is relatively large.  So it is a noise reduction system.

I wonder if one could use stacking of images to obtain a higher resolution picture of a scene.  It might involve shifting the camera ever so slightly between shots to increase the variation so that each ray is not going through exactly the same bit of glass or dust.  Perhaps lightly tapping the tripod might be enough.

So instead of doing using perhaps four 10 MPixel images taken with an 85mm lens in a 2 x 2 pano to make a 32 MPixel image (some lost due to overlap for stitching), one could make four 10 MPixel images using a 50mm lens and stack them for higher resolution, perhaps approaching 40 MPixel.

I think in principle it could be done. One way might be to super-impose the four images to align the layers (if there has been camera movement; might not be necessary to shift the camera).  From each pixel, create a 2x2 area in the super-image. For each 2x2 area, take one pixel from each of the four layers to fill out the 2x2 area.

The process I have outlined seems naive and I'd have to think about the math a bit, since there might be a more refined solution.  It seems naive, since the assignment to individual cells of the 2x2 areas seems arbitrary.
[a href=\"index.php?act=findpost&pid=109769\"][{POST_SNAPBACK}][/a]

Actually, there are a few medium format backs that automatically do 'multi-shot' captures, where they automatically move the image sensor a few microns in the relevant direction between captures. Usually it's done to get around moire fringing effects on colour sensors, but it can also be used to give greater resolution. The only problem really is that relatively few lenses have enough resolution at the film plane for it to make a noticeable difference -- some certainly do, particularly lenses made by Schneider and Rodenstock recently specifically for use with mini-view cameras, but most aren't really quite sharp enough. I dare say most of my Bronica lenses would work for it, but they are (relatively) modern designs. I've certainly had some good results making stitched panos with my Schneider shift/tilt lens on the Bronica/Megavision -- I can get about 6500x4000 out of it from two shots. I've not tried going for 4 shots, but my guess would be that I'd probably get about 6k x 6k because you can't quite shift as far if you try to do it in both directions at once. Mind you, for huge resolution there's not much that can beat the Better Light, so I tend to use that in situations where I can physically get it to the location.

I know that in astronomy it's common to do interferometry with multiple telescopes to simulate very large apertures to get very fine definition -- I'm not sure what kind of image processing they actually use. I did once do some work for a lens manufacturer who had an interferometer that they used to measure lens and mirror surfaces to insane accuracies, but it seemed to rely on doing fancy things that relied on the quantum nature of light, so I'm not sure what would be necessary.
Title: Synthetic HDR
Post by: st326 on March 30, 2007, 10:47:08 pm
Quote
I wonder if kind of the opposite could be done.
[a href=\"index.php?act=findpost&pid=109769\"][{POST_SNAPBACK}][/a]

Hmm... I'm not sure if the transform is invertible directly, or what exactly it would mean if it was. I'll think about that further. Food for thought.
Title: Synthetic HDR
Post by: Ray on March 31, 2007, 12:01:11 am
Sorry for the delay. You've got me confused here, Sarah. I thought the purpose of the exercise was to retrieve shadow detail.

Here's your tonemapped PSD version which seems to be greatly lacking in shadow detail, but does have a few blown highlights. I've converted it to grayscale to reduce file size.

[attachment=2207:attachment]

It's a bit cheeky to ask if you are working on a calibrated monitor, in view of your qualifications and expertise, but I wonder   .

This is my attempt to bring out shadow detail without blowing highlights too much, using straight processing in PS, selection, levels and curves etc.

[attachment=2208:attachment]

As you can see, I've brought out much more shadow detail than is evident in your tonemapped version whilst also preserving highlights, although I admit the shiny metal parts are a bit lacklustre. I might work some more on that.
Title: Synthetic HDR
Post by: st326 on March 31, 2007, 01:02:15 am
Quote
Sorry for the delay. You've got me confused here, Sarah. I thought the purpose of the exercise was to retrieve shadow detail.

Here's your tonemapped PSD version which seems to be greatly lacking in shadow detail, but does have a few blown highlights. I've converted it to grayscale to reduce file size.

[attachment=2207:attachment]

It's a bit cheeky to ask if you are working on a calibrated monitor, in view of your qualifications and expertise, but I wonder   .

This is my attempt to bring out shadow detail without blowing highlights too much, using straight processing in PS, selection, levels and curves etc.

[attachment=2208:attachment]

As you can see, I've brought out much more shadow detail than is evident in your tonemapped version whilst also preserving highlights, although I admit the shiny metal parts are a bit lacklustre. I might work some more on that.
[a href=\"index.php?act=findpost&pid=109808\"][{POST_SNAPBACK}][/a]

Not a bad result, Ray, but the shadow area looks a bit over-grainy -- something that seems pretty much completely absent in the synthetic HDR image. But then, that was kind-of the point of the exercise. :-)

Actually, for what it's worth, my own rendition of this photo is completely different:

(http://farm1.static.flickr.com/148/427810445_61caa99f5e_o.jpg)

My visualisation was always aimed at having completely black shadows, which is why I used the black towel as a background. This is actually a comp of two separate exposures about 2 or 3 stops apart. I initially played around with HDR merge because I had problems with highlights blowing out, and I tried using that technique to get that under control. I didn't find the result usable, but got interested in the idea of pulling that much more out of shadow areas generally. Not for this particular image, because it didn't fit with my visualisation, but just as a general principle. When I had the idea about using convolution in a binning style then using HDR techniques to re-merge the image, I looked through the images I had to hand and this one was the best I could find in terms of having a large amount of dynamic range to start with, as well as having been shot as an HDR sequence (which I didn't really use).
Title: Synthetic HDR
Post by: Ray on March 31, 2007, 01:51:43 am
Okay! Got you. Your tonemapped image does contain less noise in the shadows, when one brings them out. (Ignore my previous post if you like   .

However, I have to say, if I was converting a RAW file of this image and saw that degree of noise in my rendition below, I'd do another conversion either using luminance smoothing in ACR or noise reduction in RSP. A small adjustment at the conversion stage can have a quite noticeable effect on noise without reducing resolution to any significant degree that can't be compensated for with appropriate sharpening.

The mathematics of lower quantization errors might be clear to you, but this issue won't be resolved for me in practical terms until you can provide a RAW file that will open in ACR and preferrably RSP as well. I don't suppose you could borrow a Canon 5D and take a shot of a particularly contrasty scene, could you?  

If we are talking about fewer quantization errors in the shadows, I believe a simple dual conversion in ACR can provide a marginal improvement, but so marginal in my experience, that the added difficulties of getting a good blend without halos does not make that procedure worth the trouble, in my view. But perhaps my skills in PS are not up to the job.


Below are the lower right corners. My image, of course, is the one with less blown highlight area. The noise reduction in your tone-mapped image is significant and I failed to get a similar noise reduction in my image using Neat Image. I suppose one could argue that whatever noise reduction one achieves at the conversion stage, further noise reduction can be achieved with your method. If that's the case, I look forward to using your plu-in   .

[attachment=2209:attachment]  [attachment=2210:attachment]
Title: Synthetic HDR
Post by: st326 on March 31, 2007, 02:00:54 am
Quote
Okay! Got you. Your tonemapped image does contain less noise in the shadows, when one brings them out. (Ignore my previous post if you like   .

However, I have to say, if I was converting a RAW file of this image and saw that degree of noise in my rendition below, I'd do another conversion either using luminance smoothing in ACR or noise reduction in RSP. A small adjustment at the conversion stage can have a quite noticeable effect on noise without reducing resolution to any significant degree that can't be compensated for with appropriate sharpening.

The mathematics of lower quantization errors might be clear to you, but this issue won't be resolved for me in practical terms until you can provide a RAW file that will open in ACR and preferrably RSP as well. I don't suppose you could borrow a Canon 5D and take a shot of a particularly contrasty scene, could you?   

If we are talking about fewer quantization errors in the shadows, I believe a simple dual conversion in ACR can provide a marginal improvement, but so marginal in my experience, that the added difficulties of getting a good blend without halos does not make that procedure worth the trouble, in my view. But perhaps my skills in PS are not up to the job.
Below are the lower right corners. My image, of course, is the one with less blown highlight area. The noise reduction in your tone-mapped image is significant and I failed to get a similar noise reduction in my image using Neat Image. I suppose one could argue that whatever noise reduction one achieves at the conversion stage, further noise reduction can be achieved with your method. If that's the case, I look forward to using your plu-in   .

[attachment=2209:attachment]  [attachment=2210:attachment]
[a href=\"index.php?act=findpost&pid=109824\"][{POST_SNAPBACK}][/a]

Phew, it was a long road, but we got there in the end! ;-)

I'm uploading the DNG now. As it seems that recent versions of ACR don't screw it up, you might as well have a play with it if you like. I'd certainly be interested in seeing what NR tools can do with it. It's worth reiterating that the synthetic HDR algorithm really isn't intended to be a noise reduction algorithm, though admittedly it does seem to have that effect (quite strongly). I'll have a think about adding a bit of for-real NR filtering when I do the plugin. It could be that I could do some despeckling or median filtering or something alongside the basic algorithm. I'll have some fun with that over the weekend. :-)
Title: Synthetic HDR
Post by: st326 on March 31, 2007, 02:16:52 am
Quote
The mathematics of lower quantization errors might be clear to you, but this issue won't be resolved for me in practical terms until you can provide a RAW file that will open in ACR and preferrably RSP as well. I don't suppose you could borrow a Canon 5D and take a shot of a particularly contrasty scene, could you?   
[attachment=2209:attachment]  [attachment=2210:attachment]
[{POST_SNAPBACK}][/a] (http://index.php?act=findpost&pid=109824\")

OK,

[a href=\"http://findatlantis.com/untitled_508.dng]http://findatlantis.com/untitled_508.dng[/url]

Knock yourself out! :-)
Title: Synthetic HDR
Post by: Ray on March 31, 2007, 02:58:26 am
Quote
OK,

http://findatlantis.com/untitled_508.dng (http://findatlantis.com/untitled_508.dng)

Knock yourself out! :-)
[a href=\"index.php?act=findpost&pid=109827\"][{POST_SNAPBACK}][/a]

I suppose I've got the role of Devil's Advocate here   . It'll take a while to download through my 56k modem, so don't expect a quick reply   .
Title: Synthetic HDR
Post by: Forsh on March 31, 2007, 03:23:57 am
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Title: Synthetic HDR
Post by: st326 on March 31, 2007, 03:33:19 am
Quote
I have been using this method for a few months to extract all of the exposure I can out of single shots, then tonemapping them back. I call it "HDR Lite"   

I extract the full exposure to an exr, then tonemap it back to a 16-bit TIFF


[a href=\"index.php?act=findpost&pid=109832\"][{POST_SNAPBACK}][/a]

Very impressive images -- really striking. You have something there.
Title: Synthetic HDR
Post by: Ray on March 31, 2007, 09:48:00 am
Sarah,
I thought you were going to send me the RAW of the first image so I could see how good I could make the shadows.

The image you sent me is quite nice; a bit like the moon really. Maybe not   .

There are no noisy shadows despite the image being underexposed by a couple of stops, so that's a testament to the high dynamic range of your camera.

So what's the procedure here? I send you my attempt at a reasonable rendition using standard procedures of selection, levels and curves (and a bit of local contrast enhancement) and you send me your tone-mapped version? Right?

[attachment=2211:attachment]  [attachment=2212:attachment]
Title: Synthetic HDR
Post by: Tim Gray on March 31, 2007, 01:15:16 pm
I'm with Ray here.  There is no clipping in this image - just under exposed.  I'm not seeing where the standard PS tools and techniques are falling short.

[attachment=2213:attachment]
Title: Synthetic HDR
Post by: st326 on March 31, 2007, 03:58:04 pm
Quote
I'm with Ray here.  There is no clipping in this image - just under exposed.  I'm not seeing where the standard PS tools and techniques are falling short.

[attachment=2213:attachment]
[a href=\"index.php?act=findpost&pid=109887\"][{POST_SNAPBACK}][/a]

I'm with you *and* Ray. It's the wrong image.   It was late, what can I say other than mea culpa...

(The image I did put up was the first of a series of shots before I'd got the exposure adjusted -- I always use manual exposure, and don't bother with a light meter when I'm shooting digital, just under/over clipping indication, and I typically don't make any attempt to place the mid tones where they would be in a final print either, so my raw images look a bit weird to people who aren't used to working the way I do. The location was Arizona, it's the painted desert, but it looks weird because there was snow on the ground. I could probably claim it was Mars or Titan, but no, just Arizona. :-) )
Title: Synthetic HDR
Post by: st326 on March 31, 2007, 04:45:27 pm
Quote
I'm with you *and* Ray. It's the wrong image.   It was late, what can I say other than mea culpa...

(The image I did put up was the first of a series of shots before I'd got the exposure adjusted -- I always use manual exposure, and don't bother with a light meter when I'm shooting digital, just under/over clipping indication, and I typically don't make any attempt to place the mid tones where they would be in a final print either, so my raw images look a bit weird to people who aren't used to working the way I do. The location was Arizona, it's the painted desert, but it looks weird because there was snow on the ground. I could probably claim it was Mars or Titan, but no, just Arizona. :-) )
[a href=\"index.php?act=findpost&pid=109913\"][{POST_SNAPBACK}][/a]

OK, it's up there now. Same link as before (I had two images with the same name and picked up the wrong one -- that'll teach me to reset the counter).

In other news, the plugin is coming along. It builds and installs in Photoshop CS2, but doesn't actually do anything much yet. The algorithm is relatively simple, so it should be fairly straightforward from here (actually, creating a plugin and getting it to load is a major pain and rather more of the job than it really should be). Initially there will only be a Windows version because I don't actually own a Mac suitable for doing the port, but I think I can probably borrow one temporarily if there is any interest in having a Mac version.
Title: Synthetic HDR
Post by: Tim Gray on March 31, 2007, 05:32:17 pm
fun...

converted in LR and traditional PS stuff (nothing third party)  
2 tiffs processed from original
masked with ctrl alt ~

[attachment=2214:attachment]
Title: Synthetic HDR
Post by: st326 on March 31, 2007, 10:42:53 pm
The plugin is now available at

http://findatlantis.com/wiki/index.php/Synthetic_HDR (http://findatlantis.com/wiki/index.php/Synthetic_HDR)

It basically does what I intended in the first place, and gives far, far better results than the do-it-yourself Photoshop approach. The plugin version has no effect on the overall tonality of the image, nor does it require to know anything about the black level (it actually works across the entire tonal range). It also uses round convolution kernels, so the square-edged artifacts in the old images are also now entirely gone.

I'm currently working on the web pages for it, but it's already up there for download if anyone wants to play with an early alpha-test version. I'll post some example images shortly -- I'm quite pleased with the results I've seen so far.

Tweaking the controls:

The Amount box, in effect, sets the dividing line between the source image, which is kept sacrosanct and unaltered, and the deeper bit depth information that is calculated on the fly. Small settings of Amount favour the source image, higher settings favour the generated data. The plugin automatically selects between 3x3, 5x5 and 7x7 convolution kernels on a per-pixel basis.

The noise reduction settings basically do despeckling on what comes out of the main algorithm. The best approach seems to be to set Amount to a point where you just see a small amount of 'salt and pepper' noise with noise reduction off, then use the same value again with noise reduction set to strong. What it does is kind-of analogous to median filtering, but isn't actually implemented anything like it.

In a future version, rather than a hard dividing line between interpolated and source image data, there will probably be a softer-kneed transfer curve which should make this kind of artifact far less visible.

Caveats:

0. This is alpha test software. Expect a few rough edges. I didn't start coding it until last night, so this really is a first-chance-to-see.

1. The preview image is currently pretty much useless and not really indicative of what you'll get, so don't pay much attention to it.

2. Currently, it doesn't affect the outer two rows of pixels around the image. This is fiddlier to fix than it sounds, so I decided to leave it for the next release because it doesn't really get in the way of experimentation.

3. Selection masks are currently ignored -- the plugin affects the entire image.

4. It only currently works properly for 16-bit images.
Title: Synthetic HDR
Post by: st326 on March 31, 2007, 11:13:37 pm
Quote
fun...

converted in LR and traditional PS stuff (nothing third party) 
2 tiffs processed from original
masked with ctrl alt ~

[attachment=2214:attachment]
[a href=\"index.php?act=findpost&pid=109925\"][{POST_SNAPBACK}][/a]

Looks like a pretty decent job there, Tim.
Title: Synthetic HDR
Post by: st326 on April 01, 2007, 12:54:45 am
Sample output from the plugin

It's important to state that the plugin does not give equivalent results to the Photoshop method mentioned elsewhere in these pages -- rather, it goes to extremes to exactly preserve the tonality of the original image. For example, here's an original image, straight from the camera:

(http://findatlantis.com/wiki/images/1/17/Unmodified-image.jpg)

Running the plugin over it (with settings Amount = 50%, Noise Reduction = Strong), you get:

(http://findatlantis.com/wiki/images/4/48/Synhdr50pcntstrong.jpg)

There are no prizes for pointing out that there is no appreciable difference between the two. This is the general idea -- the algorithm has near-negligible effect on the tonality or detail present in the original image. However, if you look into the shadow areas (with the brightness and contrast enhanced with Levels) you see what the plugin has actually done:

(http://findatlantis.com/wiki/images/a/af/100pcntunmodified.jpg)

Unmodified image, 100% crop from the bottom right corner

(http://findatlantis.com/wiki/images/a/a0/100pccropsynhdr50pcntstrong.jpg)

Result from the Synthetic HDR plugin, same 100% crop and Levels adjustments

Whilst the original image shows unacceptable levels of noise and posterisation (at least to my eyes, your mileage is welcome to vary), the synthetic HDR image looks more like a deeper dynamic range version of the same image, with a little film-like grain. This effect covers the whole image through all tones, not just the shadow areas.


Relationship to 'traditional' HDR

The intent of the Synthetic HDR plugin is a little different to the HDR photography community, though it's certainly possible to borrow techniques in both directions. The main aim of synthetic HDR is to give images more usable dynamic range, allowing greater manipulation of contrast in post-processing than would normally be the case. It is certainly possible to borrow traditional HDR techniques like tone mapping, however:

(http://findatlantis.com/wiki/images/d/d7/Tonemappedresult.jpg)

Tone mapped image created by applying local adaptation in CS2

Though this image isn't particularly to my taste aesthetically, it does show off the smooth shadow detail pretty well.
Title: Synthetic HDR
Post by: Ray on April 01, 2007, 04:06:13 am
Thanks for sharing your plug-in, Sarah. I'll give it a try but I'm already getting the impression that whilst there is a perceptible reduction in noise in the shadows, it's pretty small. Shall we say, of pixel-peeping proportions.

Below are 2 crops side by side. The second has been converted in PS3 with luminance smoothing set at 80. The first is your original tone-mapped image. I applied a small and equal amount of sharpening with Focus Magic to both images.

The question is, if I use your plug-in on the conversion with luminance smoothing, will the noise reduction be more significant?
Title: Synthetic HDR
Post by: st326 on April 01, 2007, 04:14:57 am
Quote
Thanks for sharing your plug-in, Sarah. I'll give it a try but I'm already getting the impression that whilst there is a perceptible reduction in noise in the shadows, it's pretty small. Shall we say, of pixel-peeping proportions.

Below are 2 crops side by side. The second has been converted in PS3 with luminance smoothing set at 80. The first is your original tone-mapped image. I applied a small and equal amount of sharpening with Focus Magic to both images.

The question is, if I use your plug-in on the conversion with luminance smoothing, will the noise reduction be more significant?
[a href=\"index.php?act=findpost&pid=109997\"][{POST_SNAPBACK}][/a]

I don't know, try it.

Yes, the plugin's effect is subtle. Thats basically the idea -- it doesn't have anything like the level of artifacts of most denoising algorithms, and those that it does have look relatively pleasant. It also has (almost) no effect whatsoever on detail, particularly around edges, which is pretty much exactly what the standard algorithms all screw up on.

It actually works on the entire tonal range, not just in the shadows, though that's less obvious in this test image. Actually, I don't want it's effect to be obvious, ever -- I just want images to look extremely smooth and stand up to plenty of contrast tweaking in postproduction, without having nasty digital-looking artifacts from overenthusiastic median filtering.

Forget the original tone-mapped image, it's way inferior to the result from the plugin. Feel free to use the plugin to make your own, or give me a prod and I'll send you a full res image that you can take a look at.
Title: Synthetic HDR
Post by: Ray on April 01, 2007, 05:59:30 am
Quote
Forget the original tone-mapped image, it's way inferior to the result from the plugin.
[a href=\"index.php?act=findpost&pid=110000\"][{POST_SNAPBACK}][/a]


In that case, I won't bother displaying the crops that have almost identical shadow noise. (I think the image I tried to attach to the previous post might have been too big).

I've downloaded your plug-in but where do I put it? Copying and pasting into the plug-ins folder doesn't seem to do anything.
Title: Synthetic HDR
Post by: st326 on April 01, 2007, 06:01:57 am
Quote
In that case, I won't bother displaying the crops that have almost identical shadow noise. (I think the image I tried to attach to the previous post might have been too big).

I've downloaded your plug-in but where do I put it? Copying and pasting into the plug-ins folder doesn't seem to do anything.
[a href=\"index.php?act=findpost&pid=110003\"][{POST_SNAPBACK}][/a]

What version of PS are you using and on what operating system? It's built with the CS2 SDK, so I've no idea what other version(s) it might run with, if any. It could be that you're missing something that's there on mine. Also, you have to completely exit PS and then start it again in order to have it check for plugins.
Title: Synthetic HDR
Post by: Ray on April 01, 2007, 06:13:12 am
Quote
What version of PS are you using and on what operating system? It's built with the CS2 SDK, so I've no idea what other version(s) it might run with, if any. It could be that you're missing something that's there on mine. Also, you have to completely exit PS and then start it again in order to have it check for plugins.
[a href=\"index.php?act=findpost&pid=110004\"][{POST_SNAPBACK}][/a]

I've got a CS2 and CS3 versions on my Win XP x64 machine and CS2 on a 32 bit computer. The trouble is, this plug-in file of yours doesn't look like the usual plug-in format. If I paste it into the plug-ins folder, where am I supposed to find it when I open PS?
Title: Synthetic HDR
Post by: st326 on April 01, 2007, 02:59:48 pm
Quote
I've got a CS2 and CS3 versions on my Win XP x64 machine and CS2 on a 32 bit computer. The trouble is, this plug-in file of yours doesn't look like the usual plug-in format. If I paste it into the plug-ins folder, where am I supposed to find it when I open PS?
[a href=\"index.php?act=findpost&pid=110006\"][{POST_SNAPBACK}][/a]

You have unzipped it from the zip archive, yes? You should get a file synhdr.8bf inside, that's all you need. It's a 32-bit executable.

When you open PS, you (should) see a 'FindAtlantis' entry down toward the bottom of your Filters menu. It's in there, or should be anyway.
Title: Synthetic HDR
Post by: Ray on April 01, 2007, 05:12:22 pm
Quote
You have unzipped it from the zip archive, yes? You should get a file synhdr.8bf inside, that's all you need. It's a 32-bit executable.
[{POST_SNAPBACK}][/a] (http://index.php?act=findpost&pid=110097\")

Ah! A zip file. When you wrote, the plug-in is available at [a href=\"http://findatlantis.com/wiki/index.php/Synthetic_HDR]http://findatlantis.com/wiki/index.php/Synthetic_HDR[/url] , I thought that was the plug-in. It seems I just downloaded your 14kb Wiki page.

You see, I'm not all that conversant with computers   . Thanks for your trouble. I now see the plug-in at the bottom of the filters menu. I'll try it out on a few noisy high ISO images.
Title: Synthetic HDR
Post by: bjanes on April 02, 2007, 02:27:17 pm
Quote
I have been using this method for a few months to extract all of the exposure I can out of single shots, then tonemapping them back. I call it "HDR Lite"   

I extract the full exposure to an exr, then tonemap it back to a 16-bit TIFF

Examples:

Forsh,

Your examples are striking, and I especially like the first image of the young woman. What software do you use to extract the full exposure to the exr and to do the tone mapping?

Bill
Title: Synthetic HDR
Post by: Forsh on April 03, 2007, 04:54:17 pm
Quote
Forsh,

Your examples are striking, and I especially like the first image of the young woman. What software do you use to extract the full exposure to the exr and to do the tone mapping?

Bill
[a href=\"index.php?act=findpost&pid=110281\"][{POST_SNAPBACK}][/a]


Thanks Bill, I just batch process Canon RAW to OpenEXR with Photomatix. (default settings) It's really easy to overdo it, so restraint is the key with that program. With this method I get the entire exposure range of the RAW file into one file that can be worked with. After you have the EXR (or HDR) just tonemap it with any program you wish, even Photoshop.

 english in china (http://www.chinasa.ga/)
Title: Synthetic HDR
Post by: Ray on April 03, 2007, 09:52:41 pm
Quote
Thanks Bill, I just batch process Canon RAW to OpenEXR with Photomatix. (default settings) It's really easy to overdo it, so restraint is the key with that program. With this method I get the entire exposure range of the RAW file into one file that can be worked with. After you have the EXR (or HDR) just tonemap it with any program you wish, even Photoshop.
[a href=\"index.php?act=findpost&pid=110451\"][{POST_SNAPBACK}][/a]

Forsh,
Is there any ultimate dynamic range advantage in this method, or is it just an easier approach? I don't understand why it's not possible to recover the entire exposure range of the RAW file with a single conversion using appropriate adjustments of EC with shadow noise and contrast at zero, plus a bit of curves adjustment and sat. and vibrancy adjustment in CS3 Bridge.
Title: Synthetic HDR
Post by: Ray on April 04, 2007, 02:12:40 am
By the way, Sarah, that was an excellent April Fool's joke for pixel-peepers   .
Title: Synthetic HDR
Post by: st326 on April 04, 2007, 02:21:26 am
Quote
By the way, Sarah, that was an excellent April Fool's joke for pixel-peepers   .
[a href=\"index.php?act=findpost&pid=110522\"][{POST_SNAPBACK}][/a]

Eh?
Title: Synthetic HDR
Post by: bjanes on April 04, 2007, 08:59:14 am
Quote
Forsh,
Is there any ultimate dynamic range advantage in this method, or is it just an easier approach? I don't understand why it's not possible to recover the entire exposure range of the RAW file with a single conversion using appropriate adjustments of EC with shadow noise and contrast at zero, plus a bit of curves adjustment and sat. and vibrancy adjustment in CS3 Bridge.
[{POST_SNAPBACK}][/a] (http://index.php?act=findpost&pid=110490\")

Forsh and Ray,

One obvious difference in Forsh's method is that he is converting from raw using the Photomatix software and then editing in a 32 bit floating point linear space. If you are using Bridge and ACR, the internal working space is 16 bit linear. On an intuitive level, it would seem to me that the ACR 16 bit linear space would have all the headroom necessary to process the 12 bit linear raw file. If you have a true HDR image, then 32 bit floating point would be necessary.

I note that in PSCS3 one can use the mode command to convert to 32 bit and save the file in the OpenEXR format. According to a [a href=\"http://www.anyhere.com/gward/hdrenc/hdr_encodings.html]post[/url] by Greg Ward, the OpenEXR format file can use single precision (32 bit) IEEE floating point or a half precision (16 bit) format for storage, but 32 bit IEEE floats are presumably used for processing, since that is the format supported by current CPU hardware. Some graphics cards now support the half precision format in hardware. PSCS2 can't store in the OpenEXR format, but it does support 32 bit floating point and I think that the PSD or Radiance formats that it does support for storage would be equally suitable.

It would appear that PS users could use Forsh's methods without investing in the Photomatix software, but I have no idea of which workflow would be better. Or perhaps one could get similar results from ACR4 as Ray suggests. An interesting topic for discussion.

Bill
Title: Synthetic HDR
Post by: Ray on April 04, 2007, 09:30:20 am
Quote
Eh?
[a href=\"index.php?act=findpost&pid=110525\"][{POST_SNAPBACK}][/a]

You mean it wasn't an April Fool joke? You did post the link to the plug-in on April 1st. Was that just a coincidence?  
Title: Synthetic HDR
Post by: rslv on April 04, 2007, 10:58:42 am
Sarah, thank you for creating and sharing this. Much appreciated.
Would you mind posting a workflow example? I'm not entirely sure about your process.
Title: Synthetic HDR
Post by: Pete JF on April 04, 2007, 11:32:53 am
Man, I'm interested in some light HDR technique but this thread has left me spinning. My terminology/knowledge is lame in this area and I do not understand what is going on here. What Forsh is doing looks pretty good. My needs are simple..I'd just like to open up some areas in certain mages in a simple subtle way. I'm interested in what, you, Sarah, are presenting here but I'm not sure I understand what is different.

Obviously Forsh is using one image, one exposure..I don't understand what happens after that. Are you creating several interpretations of the exposure in a RAW processor and then outputting those for HDR treatment... Anyone care to explain in less terminology oriented terms?




Some of the HDR stuff I've seen draws WAY to much attention to the processs.
Title: Synthetic HDR
Post by: Eric Myrvaagnes on April 04, 2007, 08:19:51 pm
Quote
Man, I'm interested in some light HDR technique but this thread has left me spinning. My terminology/knowledge is lame in this area and I do not understand what is going on here. What Forsh is doing looks pretty good. My needs are simple..I'd just like to open up some areas in certain mages in a simple subtle way. I'm interested in what, you, Sarah, are presenting here but I'm not sure I understand what is different.

Obviously Forsh is using one image, one exposure..I don't understand what happens after that. Are you creating several interpretations of the exposure in a RAW processor and then outputting those for HDR treatment... Anyone care to explain in less terminology oriented terms?
Some of the HDR stuff I've seen draws WAY to much attention to the processs.
[a href=\"index.php?act=findpost&pid=110592\"][{POST_SNAPBACK}][/a]
Me too! I keep wondering whether you can get the same results just using the highlight-shadow tool.
Title: Synthetic HDR
Post by: Tim Gray on April 04, 2007, 09:07:18 pm
Try this simple technique.

Process the original RAW 2 times, adjusting the exposure - one over exposed to bring out the shadows and one underexposed to reduce highlight clipping.

Open the under exposed image and copy the over exposed image on top.

With the top layer selected (the over exposed one), hit ctrl alt ~  this selects the brightest pixels of the over exposed layer, then Delete.  (after ctrl alt ~ you could hit the mask icon and go from there).

The problem doing this in PS HDR with one image is that you have to edit the exif to fool PS into thinking there are 2 seperate exposures.

In general, using lightroom, I don't have to do this, but the original sample from Sarah was a bit extreme and so this was easier than fussing with the curves and highlight/shadow stuff in LR.
Title: Synthetic HDR
Post by: pobrien3 on April 04, 2007, 10:47:55 pm
By processing the RAW several times and blending them as if you had a true HDR image, you can achieve the look that Forsh gets which is decidedly different than using one 'development' of the file and using curves / shadow/highlight.  I don't say better or worse, just different.  I personally like to use this method for some images to boost local contrast before converting to B&W - you can get quite a dramatic effect: I like what it does to skies and clouds, and you can use it to boost textures.  If it's subtlety you're after, this technique must be used very sparingly and with great care - in such cases I would try PS curves etc. first.  Below are a couple of very overdone images to illustrate the effect.

There's an excellent tutorial on using this technique (and some stunning photos) with Photomatix by Pete Carr here (http://www.vanilladays.com/hdr-guide/) - I particularly like the images of my home city, Liverpool on his site.

[attachment=2236:attachment]  [attachment=2237:attachment]  [attachment=2238:attachment]
Title: Synthetic HDR
Post by: neil on April 04, 2007, 11:48:03 pm
I'd be interested in your porting your plugin to a mac....

I'm not sure if I have the time for 32bit floating point something or other....but I'll look into it - cause I want to get a similar, but smoother look without having to shoot polaroid spectra.

I developed a faux HDR workflow using Dr Brown's Place a Matic (http://www.russellbrown.com/tips_tech.html) and the attached actionset. [attachment=2240:attachment]   Its pretty handy and customizable at each stage of the workflow, cause sometimes a linear selection of the highlight or shadow conversion isn't right.  So you can alter the development settings in ACR while altering mask tonalities and the mix between the two files with custom dodging and burning. The actionset finishes with some pretty handy tricks to get midtone contrast returned.  I'd love to hear if you experts have any suggestions for improvement iworkflow steps in the actions to give better tonal qualities.

I developed the need for a quick and accessable workflow after shooting in some hard desert light:
(http://web.mac.com/ncstudio/forums/canyon_10-7_309.jpg)

(http://web.mac.com/ncstudio/forums/canyon_10-7_287.jpg)
Title: Synthetic HDR
Post by: st326 on April 04, 2007, 11:55:32 pm
OK, the basic workflow (and no, it wasn't an April fool's joke) is something like:

1. Capture image, get it into Photoshop by some appropriate means.

2. Make sure that the image is in 16 bit mode.

3. Run the plugin. If you can see any difference to the image as-is, assuming a typical 8-bit per colour plane graphics card, you've probably got the plugin set to be too aggressive. You should only see any difference if you up the contrast significantly. I keep reminding people that the point of the plugin *isn't* noise reduction, though it does do that to some extent. A good trick is to zoom in on some shadow detail, create a (temporary) levels layer and set it so that the shadow area is very visible. Tweak the plugin to get smooth shadow detail, but no effect to the overall tonality or sharpness of the image.

At this point, it kind-of depends on what you want to do. If you want to do tone mapping, put the image in 32 bit mode then back to 16 bit mode again, which will cause the tone mapping dialogue to appear -- you'll need to select Local Adaptation from the drop down box. This will let you perform the kind of tone mapping that's popular in the HDR community -- it's annoying that you can't just invoke it directly on a 16 bit image, but it just seems to be the way PS is designed.

One thing that's interesting with this plugin is that it seems to behave quite differently depending on what kind of source material you feed it, so I think I'll have to add a few more tweakable controls to the next version. I've tested it mostly with images from my Megavision monochrome back and from my Better Light scan back -- neither of these things have a Bayer matrix, so there is none of the usual colour interpolation going on down at the pixel level. I tweaked the code based on my own images, and set it up so that when it found fine detail it backs off, leaving it unchanged. However, it seems that the difference from pixel to adjacent pixel in both the Better Light and the Megavision images is substantially larger than that from interpolated colour data from Bayer matrix sensors, so in this case there wasn't anything like as much fine detail as I was seeing from my test images. I suppose this shouldn't be any surprise, because this is exactly what theory would predict, but whatever the cause I'll have to add some kind of fiddle factor for this tendency. This difference isn't so visible to the naked eye, but it's certainly there in the numbers, and the plugin works on the numbers. Strictly speaking, the red and blue channels have half the resolution in each axis (i.e. only 25% of the information), and the green channel has only 50% of the information of a non-Bayer image, even ignoring the effect of antialiasing filters, so this significantly limits the maximum slew rate between adjacent pixels, even when that slew is just caused by noise.

I suspect that two quite different algorithms are going to be necessary -- one for non-Bayer imagers, and one for conventional imagers.
Title: Synthetic HDR
Post by: st326 on April 05, 2007, 12:09:01 am
On the subject(s) of tone mapping and noise reduction, I'm going to have a go at putting a plugin together that does image manipulation in the spectral domain (i.e. take the source image, do a 2D FFT on it, mess with the spectrum, then do an inverse FFT to map it back to a conventional image). Lots of standard operations on images become trivial in the spectral domain -- sharpening, blurring, etc. are trivial, because they map on to something not much harder than cropping or at worst dodging and burning in the spectral domain. However, there's a lot more that can potentially be done -- transforming the spectrum nonlinearly should make it possible to do spectral noise reduction (as commonly used in the audio world) on a 2D image. I've no idea how well this will work in practice, but there is a good chance that it would be extremely effective. I've written audio noise reduction code (in a past life) that could pull intelligible speech out of something that sounds like 99% hiss, 1% signal, so given the amount of noise we usually have in images it's probably going to work pretty well, if it works at all.

Interestingly, tone mapping has a parallel in the spectral domain too. In effect, with tone mapping, you're reducing the contrast of large scale features in the image, whilst simultaneously increasing the contrast of smaller scale features. In the spectral domain, this is no harder than dodging and burning (or maybe applying curves). Should be a fun plugin anyway. It might also provide an alternative means of upping effective bit depth for Bayer images, because that too should be a lot more precise in the spectral domain.

(By 'spectrum' and 'spectral' I'm referring to the signal processing terms -- this is completely unrelated to the colour spectrum of the image itself)
Title: Synthetic HDR
Post by: Ray on April 05, 2007, 12:15:28 am
Quote
Try this simple technique.

Process the original RAW 2 times, adjusting the exposure - one over exposed to bring out the shadows and one underexposed to reduce highlight clipping.

Open the under exposed image and copy the over exposed image on top.

With the top layer selected (the over exposed one), hit ctrl alt ~  this selects the brightest pixels of the over exposed layer, then Delete.  (after ctrl alt ~ you could hit the mask icon and go from there).

The problem doing this in PS HDR with one image is that you have to edit the exif to fool PS into thinking there are 2 seperate exposures.

In general, using lightroom, I don't have to do this, but the original sample from Sarah was a bit extreme and so this was easier than fussing with the curves and highlight/shadow stuff in LR.
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Tim,
You're a gem. I just tried your method on a couple of 'real' HDR exposures, the view out of my $4 a night hotel room in Nepal, bracketed, and the halos around the edges of the window frame have disappeared. Michael should include this trick in his tutorial on blending.

[attachment=2241:attachment]


I've just realised I forgot the Gaussian blur in the above blended shot. Must have had a few too many glasses of wine when I posted that. I have great difficulty in avoiding halos at the edges of the window frames in shots like this. Setting a high pixel radius in Gaussian Blur helps but creates other 'lack of contrast' and 'uneven contrast' problems in the view out of the window. I was hoping Tim's method was a quick fix but it doesn't seem to adress this problem.
Title: Synthetic HDR
Post by: Slough on April 05, 2007, 08:19:02 am
There is another way to 'recover' highlights and shadow detail using only one image. Obviously you cannot recover anything that is not there, so really this is contrast masking. Here is the tutorial:

http://www.nwpphotoforum.com/ubbthreads/in...ston/roman2.php (http://www.nwpphotoforum.com/ubbthreads/information/php/2007_Articles/rjohnston/roman2.php)

I find this can work really well, and it does not unduly flatten the image i.e. it preserves local contrast.

I would prefer an automated method as the above one requires some thinking, and hence takes some time, but it does the job.
Title: Synthetic HDR
Post by: st326 on April 05, 2007, 01:35:53 pm
(http://findatlantis.com/wiki/images/a/a6/Splitrock-colour-synhdr-web.jpg)

Split Rock, Joshua Tree National Park

Cambo Legend 4x5, Better Light Super-6K, 8000x6000x14-bit colour, single capture (approx. 300MB). The original has extreme contrast -- the sun was directly behind the rock, just before sunset. Processed as follows:

   1. Synthetic HDR plugin, 3% amount, strong noise reduction.
   2. Changed to 32-bit mode.
   3. Changed back to 16-bit mode with local adaptation, 1 pixel radius, gamma at maximum, curves unaltered from default (i.e. linear)
   4. Created levels and curves layers, tweaked until it looked somewhere close
   5. Created a colour balance layer, tweaked to remove a slight blue cast
   6. Created a second curves layer, tweaked to darken the sky slightly. Hand-painted mask, then blurred mask with a 250 pixel Gaussian blur filter.
   7. Did mild sharpening with Smart Sharpen (it didn't need much)
   8. Duplicated the image layer, applied a 150 pixel Gaussian blur, then set the layer to affect colour only. Created a mask, inverted it, then painted over areas of the plants that had motion artifacts due to fairly strong wind.
   9. Crop, copy, downsize for web use, slight unsharp mask to help compensate for the (huge) size reduction.

What looks like it might be noise in the rock surface areas isn't -- it's actually the grain of the rock itself. Downsizing the image for posting here meant reducing both dimensions by roughly 10:1, which is a 100:1 reduction in information, so at this size, if you can see it, it was there.
Title: Synthetic HDR
Post by: pobrien3 on April 05, 2007, 01:40:36 pm
Slough, if you go for this method there are better ways of making the mask than using the colour range selection tool.  The technique Tim Gray described above is one such method, using luminosity masks is another - the one I prefer.  Take a look at this tutorial (http://www.goodlight.us/writing/luminositymasks/luminositymasks-1.html) by Tony Kuyper, who also kindly provides the actions required to make the masks.

Peter
Title: Synthetic HDR
Post by: Slough on April 05, 2007, 02:49:12 pm
Quote
Slough, if you go for this method there are better ways of making the mask than using the colour range selection tool.  The technique Tim Gray described above is one such method, using luminosity masks is another - the one I prefer.  Take a look at this tutorial (http://www.goodlight.us/writing/luminositymasks/luminositymasks-1.html) by Tony Kuyper, who also kindly provides the actions required to make the masks.

Peter
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Thanks. Roman's works well but I will give your link a try. Leif
Title: Synthetic HDR
Post by: rslv on April 05, 2007, 06:23:06 pm
Sarah, thanks for posting the workflow details.
Your image rocks!  
Title: Synthetic HDR
Post by: Pete JF on April 05, 2007, 08:12:12 pm
I tried the process the Slough suggested using a shadow and a highlight output from RAW and Color Range to generate selections>mask and got good results for an image that I've been fighting with in a more conventional way.. I was thrilled to arrive at something halfway decent in about a half an hour or so...sheesh. I think you have to stay subtle with this trick or things start looking funny.

Cool to be able to find quite a bit of control in a short period of time. The image was exposed to hold the brightest part of the sky, basically, the sun behind a fairly thin layer of clouds. Im hoping to find some time tonight to try all the other stuff in this thread. Sarah? Does your plug-in work on a mac? is it just a simple PS plug in?

(http://i122.photobucket.com/albums/o274/rentChicago/Northhdrlite.jpg)
Title: Synthetic HDR
Post by: st326 on April 06, 2007, 01:45:43 am
Quote
I tried the process the Slough suggested using a shadow and a highlight output from RAW and Color Range to generate selections>mask and got good results for an image that I've been fighting with in a more conventional way.. I was thrilled to arrive at something halfway decent in about a half an hour or so...sheesh. I think you have to stay subtle with this trick or things start looking funny.

Cool to be able to find quite a bit of control in a short period of time. The image was exposed to hold the brightest part of the sky, basically, the sun behind a fairly thin layer of clouds. Im hoping to find some time tonight to try all the other stuff in this thread. Sarah? Does your plug-in work on a mac? is it just a simple PS plug in?

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Nice image!

The plugin currently is Windows-only. Hopefully a volunteer will come along to port it, but more work is needed on the original first -- currently it works very well on Megavision images, pretty well on Better Light images, and not that well on everything else, so it needs tweaking based on some different source material. Basically, if there isn't that much fine detail at the pixel level, it is a bit too aggressive with its smoothing. The Megavision images have at least 2 to 4 times as much pixel-level detail as each colour plane of an image from a Bayer sensor, so I need to do some changes to accommodate that difference. I should be able to iron this out given a bit of messing around time, hopefully this weekend. I'll also add some shadow/midtone/highlight settings so you can back off the level on mid tones and increase it in the shadows, which should also help.
Title: Synthetic HDR
Post by: Pete JF on April 07, 2007, 12:32:31 pm
Thanks Sarah, I appreciate that.

I had a feeling from the beginning of the thread that your plugin was for PC only , oh well. There's another software in this section of this board that looks kind of neat that's being offered up for free..pc only of course. It's that "Tonehacker" that a guy is nice enough to offer as a freeware. No biggy..If you get it ported to Mac let us know, I'd like to try it. In the meantime I'll mess with some of these lite HDR tips. You seem like you know your way around the guts of some software code.
Title: Synthetic HDR
Post by: st326 on April 07, 2007, 08:15:08 pm
Quote
Thanks Sarah, I appreciate that.

I had a feeling from the beginning of the thread that your plugin was for PC only , oh well. There's another software in this section of this board that looks kind of neat that's being offered up for free..pc only of course. It's that "Tonehacker" that a guy is nice enough to offer as a freeware. No biggy..If you get it ported to Mac let us know, I'd like to try it. In the meantime I'll mess with some of these lite HDR tips. You seem like you know your way around the guts of some software code.
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Yes, please don't take it too personally that I'm not offering a Mac version yet. To do so would involve buying a mac, development tools and yet another Photoshop license, which would cost $$$, so since there is no likely financial return on that, I can't really justify it. As a consequence, it's probably not going to happen unless my day job randomly requires me to start writing software for the Mac platform. This isn't impossible (my boss mentioned it the other day actually), but it's basically the only way I'd get my hands on the necessary hardware unfortunately.