HDR Frustration

[feppe]

But that is exactly what happens when tonemapping huge dynamic range images. They are manipulated to the extreme (in small ranges of brightness) to creata a perceptually convincing image. Most of the image tones are only subjected to small contrast enhancements, but it's those selective areas that need all the bits they can have to avoid micro posterization. Typical problem areas are bright sky areas and deep shadow areas.

I'm talking about the final result; to rephrase there's no compelling reason to produce images for reproduction in 32 bit space. 32 bit imaging might be required in some workflows as an interim step to get to a useful 16 bit image. For example, I understand all HDR image packages use 32 bit operations. But one can produce "perceptually convincing" images from outrageously high dynamic range subject matter by manual blending, while staying securely in 16-bit space throughout the entire workflow.

[Guillermo Luijk]

But that is exactly what happens when tonemapping huge dynamic range images. They are manipulated to the extreme (in small ranges of brightness) to creata a perceptually convincing image. Most of the image tones are only subjected to small contrast enhancements, but it's those selective areas that need all the bits they can have to avoid micro posterization. Typical problem areas are bright sky areas and deep shadow areas.

I agree, but 16-bit integer can also encode a huge DR, just need to make use of gamma expansion (on the left linear levels per stop in a linear encoding, right gamma 2.2):



We are talking about 20 stops of DR sufficiently well defined with 16-bit integer, and we could even improve this by using a higher gamma curve. This 16-bit integer TIFF file encodes a scene of >16 stops of real DR, and shadows can be lifted by 15 stops with no posterization.

So the point of using 32-bit floating is to make easier and/or more efficient from a software point of view to make calculations with linear values. But for the purpose of just encoding a lot of DR, there is no technical need for 32 bit.

Regards

[Bart_van_der_Wolf]

So the point of using 32-bit floating is to make easier and/or more efficient from a software point of view to make calculations with linear values. But for the purpose of just encoding a lot of DR, there is no technical need for 32 bit.

Hi Guillermo,

Yes, I agree that for a final result, 16-b/ch is plenty, even if there will be some colormanagement involved for output (e.g. printer profile conversion). I don't see any issues in that stage of the workflow.

But when the images are going to be a basis for further work, they offer sometimes a bare minimum quantization precision. Blending of colors in Photoshop layers is e.g. best done with a linear gamma setting in the P.S. Color settings, and linearizing pre-gamma adjusted integer values and re-introducing gamma for the final output risks introducing posterization or luminosity shifts in smooth gradients or sharp edges. Nothing to get too exited about, as long as one is aware of what the results can be, and how to avoid nasty surprises.

Image math is customarily done in linear gamma colorspace (e.g. Lightroom apparently does it for some operations by default), and Photoshop offers the choice for some of the blending operations. The HDR renderers work in linear gamma and so do good video/graphics cards when mapping textures.

Cheers,
Bart

[RFPhotography]

No, not even close really. It's true today's inkjets can exceed Adobe RGB in certain areas (but not total volume); but that's a far cry from reproducing all of ProPhoto RGB.

Not according to Epson with their newer x900 models.  I went to an Epson Print Academy seminar shortly after the x900 models came out.  Schewe, Rodney, Caponigro et al were the speakers and I can't remember who it was showed gamut overlays of the x900 inkset on Exhibition Fibre and ProPhoto and the ProPhoto gamut was nearly all encompassed.  

But putting that aside, the gist of the argument I was making was that technology is improving.  So why not be ready for it?  Sure, if I've got my original RAW files I can always go back and reprocess images to take advantage of technologicial improvements but why do that extra work when simple steps can be taken today to be ready for it down the road.

Bart, what setup do you have in PS that allows you to work in a linear gamma environment?  Your links aren't working either.  Both have an extra 'http' at the front.  When I remove the extra 'http' from the luminosity shifts link, I'm eventually taken to a wikipedia article on hypertext transfer protocol.

Feppe, how long did you spend at the computer creating that image?

[feppe]

But putting that aside, the gist of the argument I was making was that technology is improving.  So why not be ready for it?  Sure, if I've got my original RAW files I can always go back and reprocess images to take advantage of technologicial improvements but why do that extra work when simple steps can be taken today to be ready for it down the road.

While I agree when it comes to gamut, I disagree when it comes to bit depth. I'm positive I can see more colors than today's printers can produce, perhaps all the way up to Prophoto, therefore I use Prophoto to future proof my workflow. But I'm also positive I can't see the gradation of colors in a 32 bit image - it's probably much closer to 16 bits than 32 bits, perhaps even lower than 16 bits.

Therefore 32 bit imaging is overkill, and since the files are a pain to work with due to the need for tonemapping, I stick with 16 bit imaging as it's just a future proof as Prophoto.

[RFPhotography]

And that's fine.  I don't know that I can see all the gradation in a 32 bit image either.  I don't know how much gradation the human visual system can perceive.  It's going to be different for every person.  I know trained printers who claim they can see unsmooth gradation in 16 bit prints.  I have no way to verify that so have to take them at their word. 

I really don't want to get into an 8 vs 16 vs 32 bit urinating contest.  It's almost as productive as Canon vs Nikon, ETTR vs non-ETTR, UniWB vs regular WB.   

To suggest HDR files are a pain to work with simply because of the need to tonemap them into a visible range seems a bit of an odd argument.  Perhaps you've got your manual blending down to a smooth science and can crank off large, manually blended panos in a few minutes but I don't think most people could so I'm not sure the amount of work or hassle involved in the two methods is necessarily the issue.  It comes down, in that case, to a comfort factor.  And that's fine too.

[JeffKohn]

Not according to Epson with their newer x900 models.  I went to an Epson Print Academy seminar shortly after the x900 models came out.  Schewe, Rodney, Caponigro et al were the speakers and I can't remember who it was showed gamut overlays of the x900 inkset on Exhibition Fibre and ProPhoto and the ProPhoto gamut was nearly all encompassed.

I suspect your memory is a little fuzzy and they were actually comparing to Adobe RGB (which still has more total gamut volume, but doesn't fully contain the gamut of today's inkjets in certain areas). No current inkjet, including the Epson x900's, comes even close to encompassing ProPhoto; and I don't believe Schewe et al would have made such a claim.

But putting that aside, the gist of the argument I was making was that technology is improving.  So why not be ready for it?  Sure, if I've got my original RAW files I can always go back and reprocess images to take advantage of technological improvements but why do that extra work when simple steps can be taken today to be ready for it down the road.

I don't really disagree. I use 16-bit ProPhoto RGB and print through Canon's 16-bit plugin. I'm all for making the most of what technology can do. But when incorrect statements go unchallenged they have the potential to become "internet facts".

[JeffKohn]

While I agree when it comes to gamut, I disagree when it comes to bit depth. I'm positive I can see more colors than today's printers can produce, perhaps all the way up to Prophoto, therefore I use Prophoto to future proof my workflow. But I'm also positive I can't see the gradation of colors in a 32 bit image - it's probably much closer to 16 bits than 32 bits, perhaps even lower than 16 bits.

Therefore 32 bit imaging is overkill, and since the files are a pain to work with due to the need for tonemapping, I stick with 16 bit imaging as it's just a future proof as Prophoto.

It's not about color gradations. The 32-bit formats are meant to encompass huge dynamic range in linear encoding, as Guillermo said. If I'm not mistaken, the common HDR formats have their roots in CGI and 3d rendering, and the 32-bit floating point format was chosen for good reasons.

Photographers (or I guess Photomatix) kind of co-opted these formats for our uses, they weren't originally designed with high-contrast photography in mind.

One could argue that 32-bit floating point formats are superior. The fact that the files are more trouble to work with is the fault of our software, more than the file formats. As computers get faster, the reasons for staying with integer math diminish (the biggest reason it's here for the foreseeable future is legacy code more than anything else).

[feppe]

To suggest HDR files are a pain to work with simply because of the need to tonemap them into a visible range seems a bit of an odd argument.  Perhaps you've got your manual blending down to a smooth science and can crank off large, manually blended panos in a few minutes but I don't think most people could so I'm not sure the amount of work or hassle involved in the two methods is necessarily the issue.  It comes down, in that case, to a comfort factor.  And that's fine too.

I think it's more about what we're used to, and should have qualified my statement that blending works better for me. I've tried "proper" HDR techniques and programs, and none of them produce results I like - I feel constrained by the global adjustments, and just can't get my head around all of the rather abstract sliders. Granted, I haven't done much experimenting, as using layers and blending is much easier for me. For example, I use PTGUI's exposure fusion as an extra layer, as it does produce good results in some part of the image, while flattening others too much.

Agree fully on the pointlessness of the almost-religious discussion of 32 bit vs 16 bit

[RFPhotography]

It may be, Jeff.  Unlike many, I don't profess to be perfect.

[Dick Roadnight]

May I ask how you deal with leaf motion with manual blending? Do you simply choose the image with the best overall exposure of the leaves, and then mask them out completely in the other image layers?

In this crop you can clearly see that branches (not just leaves) moved between shots... the darker branches are from the darker "sky" shot.

This is about a 1 Mpx crop from the background of a 50Mpx picture.

I think I created a "select colour" mask from the sky in the lighter (not sky) picture... and merge ignored the white (sky) where the branches were in a different position... What I was doing was using the sky from one picture (of a minibus, previously posted, I think) and merged it into another. You can see some purple fringing, but it was fit for purpose.

When I got the latest version of phocus, I could recover the highlight so well I did not need to HDR.

[Brad Smith]

In this crop you can clearly see that branches (not just leaves) moved between shots... the darker branches are from the darker "sky" shot.

This is about a 1 Mpx crop from the background of a 50Mpx picture.

I think I created a "select colour" mask from the sky in the lighter (not sky) picture... and merge ignored the white (sky) where the branches were in a different position... What I was doing was using the sky from one picture (of a minibus, previously posted, I think) and merged it into another. You can see some purple fringing, but it was fit for purpose.

Thanks, Dick. The mask based on select color is probably a good choice when the motion is against the sky.

[DougHerrick]

I am glad to see all this interest in HDR. I've been working with it for a couple of years now and continue to learn new stuff. Getting back to the original post: It is a process and it starts from the ground up, good tripod, lins and camera. Expand your brackets to 2 stops instead of one. Shoot in RAW and process them in the conversion software of your choice (Photomatix should not be used as a raw converter) you should maintain your exposure differences while correcting for white balance (I select all three images but only correct the average exposure image, applying the same adjustments to all the images). Convert your files to .tiff or .psd. Now you can combine these images with the software of your choice (I use Photomatix). After you've finished creating your new HDR file put some polish on it using Photoshop or Lightroom (I use both). It's a time consuming process and the results can be surprising, some good, some bad. It takes time to understand all the interrelated adjustments, just keep trying, you'll get it!

Guillermo:  I have always been interested in your Zero Noise, but could never understand the process. Any changes to your User Interface?

Gramps

This is my present stage of development:

[JeffKohn]

Anybody see the PR for Nik's new "HDR Efex Pro" software? It wasn't clear to me from the press release whether it's just a psuedo-HDR contrast/detail enhancer in the same vein as Topaz Detail, or if it can actually tonemap 32-bit HDR files.

[RFPhotography]

As far as I can tell, Jeff it's a plugin that contains a full application that opens inside Photoshop.  It'll work on single or multiple image merges.  What I can't figure out, like you, from anything I've seen or read is whether it will work on exisiting 32 bit images.  I've not seen anything on whether it's a true HDR app, creating 32 bit image files or whether it's an exposure blending app that never leaves the 8 or 16 bit space.  Either way, at $160 it's more expensive than other options on the market, much more expensive than some. 

[Dick Roadnight]

This is my present stage of development:

Is this how you wanted it to turn out?

I would want more contrast - I thought Photomatrix gave you control.

[RFPhotography]

I thought Photomatrix gave you control.

It does, yes.  Depends on the result that's desired.  But PM isn't the last step in the process generally, either.  Many people tonemap their 32 bit images then bring the resulting LDR images back into their image editor of choice for additional work.  They get a good working version through the HDR tonemapping process (i.e., treat it like an enhanced RAW file), then do final work in the low bit depth world as usual.

[DougHerrick]

Thank You Mark, that's exactly what I do. Photomatix is just one stop along the way. As I noted in my original reply. I may be pretty whacked out, but I adjust in PM by using the histogram. Rule #1: No clipping. The PM Processed image then moves to PS for Noise reduction and a simple curves adjustment (and object removal, if necessary) then on to Lightroom for minor tweaks and possible cropping.
Regarding the observed lack of contrast; my objective is to produce what I call soft detail, the art of defining the contrast via color tone, not so much luminosity (light to dark). Think: straight curves.

Here's another example from the same shoot. The location is Savannah, Georgia.

Gramps

[RFPhotography]

As a follow up to my earlier comments regarding Nik's new offering, I sent an email to their support group this morning.  They've confirmed that it's a full HDR application hosted inside PS.  It will create 32 bit files on merge and it can tonemap existing 32 bit files.

[JeffKohn]

As a follow up to my earlier comments regarding Nik's new offering, I sent an email to their support group this morning.  They've confirmed that it's a full HDR application hosted inside PS.  It will create 32 bit files on merge and it can tonemap existing 32 bit files.

Good to know. I agree it's on the expensive side (Nik plugins always are). The thing that has me intrigued about it is using the U-Point technology for local adjustments, as well as their claims about halo suppression.