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Author Topic: shooting to the right/digital blending  (Read 19497 times)

thierrylegros396

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shooting to the right/digital blending
« Reply #20 on: October 06, 2006, 03:02:48 am »

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The histogram is based on a jpeg conversion and the jpeg conversion and the appearance of the histogram is influenced by the in-camera contrast settings. The RAW image, however, is not influenced by such settings.

That's why I'm using "+1 color saturation" and minimum contrast in Jpeg settings, wich gives me more accurate histograms.
But it's not the perfect solution.
Still trying to know when to use luminance and RGB histogram for the more accurate results.
And discovered that Silkypix has a very good recovery feature for blown sky.
Want to compare it with Lightroom revovery to know which is the best.

Thierry
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Ray

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« Reply #21 on: October 06, 2006, 08:08:12 am »

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Although hard disk storage isn't an issue, CF storage is, as is processing time - which includes downloading the redundant files, building the thumbnails and actually executing some kind of mental judgement process against the files all of which chews up "real" time.

[a href=\"index.php?act=findpost&pid=79217\"][{POST_SNAPBACK}][/a]

Tim,
I can see that CF storage might be an issue (as well as write speed) if you are, for example, in the habit of taking multiple shots at the same exposure to capture the perfect moment in a football game. But for landscape shots, there should be no problem. At present I'm in Siem Reap photographing the temples at Angkor Wat. I have 2x4gb cards, 2x2gb cards and 2x1gb cards. Despite this place being a photographer's paradise (and I bracket everything), I rarely fill in 12 hours of shooting more than 2x4gb cards, with my 12.8mp 5D. Downloading to my laptop takes more time of course, but not my time. It's an automatic process.

Sorting and assessing the images does take more time, but Hey!, you don't want something for nothing, do you?  
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John Sheehy

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« Reply #22 on: October 06, 2006, 09:12:52 am »

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That's why I'm using "+1 color saturation" and minimum contrast in Jpeg settings, wich gives me more accurate histograms.
[a href=\"index.php?act=findpost&pid=79281\"][{POST_SNAPBACK}][/a]

+1 saturation is going to cause saturated colors to blow out in the review/histogram much faster than the RAW.
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John Sheehy

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« Reply #23 on: October 06, 2006, 09:15:30 am »

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IMHO the "best" solution would be a histogram/display that accurately reflects the DR captured by the RAW file.
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That should have been on the very first digital to offer RAW output.  I'm still waiting.  These manufacturers play us for idiots.
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Ray

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« Reply #24 on: October 06, 2006, 09:40:07 pm »

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That should have been on the very first digital to offer RAW output.  I'm still waiting.  These manufacturers play us for idiots.
[a href=\"index.php?act=findpost&pid=79308\"][{POST_SNAPBACK}][/a]

It's surprising how many people still shoot jpegs with their DSLR. If they want good sky detail, they'll simply underexpose the shot, which is not good for the shadows of course.

Whilst a RAW based histogram would be an improvement, it would not necessarily be a complete solution without a live preview, as you get with EVFs on P&S cameras. If you don't have a live histogram and you have the time to take a shot, study the RAW histogram and decide the exposure needs fine tuning and take another shot, then you're just as well off estimating exposure from the current rather inaccurate histogram and autobracketing. In fact, you're probably better off.

I'd rather have a shot that is over or underexposed by a small amount (with respect to ETR) that accidentally captured the best moment, than a perfectly exposed shot that missed the moment by a 5th of a second. If you're in aperture priority mode, there's also the possibility of misjudging the shutter speed required to freeze subject movement. The underexposed shot with its faster shutter speed might sometimes be the preferred one. Some of one's best shots can be unexpected, unanticipated or simply sheer accidents.

....and I didn't even mention the potential of composite images from the bracketed shots. Normally, blending different exposures to increase dynamic range requires the use of a tripod. However, mixing feathered selections can sometimes be done seamlessly without affecting the integrity of the scene. I'd be interested in any suggestions forum memebers might have as to the best methods of doing this. I've not yet come across a program that can successfully align hand-held shots for pixel sharp blending. There often seems to be a certain amount of rotation and twisting that takes place between hand-held bracketed shots within that full second or so time frame, especially when one is precariously perched on a slippery, moss-covered rock slab at a 45 degree angle to the ground.
« Last Edit: October 06, 2006, 10:07:11 pm by Ray »
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Mark D Segal

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shooting to the right/digital blending
« Reply #25 on: October 06, 2006, 11:33:53 pm »

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My point is that there isn't an easy way.  You have to play with the exposure, brightness, contrast and shadow sliders until you get what you want.
[a href=\"index.php?act=findpost&pid=79072\"][{POST_SNAPBACK}][/a]

Actually, it isn't all that hard, nor need it be very time-consuming at all, if the work-flow is designed logically and efficiently.

First I agree there is no loss of data unless an ETTR is clipped. Second, apparent over-exposure or apparent loss of saturation is easily compensated in PS because the information is there. Third, images with desirable data in the quartertones can become posterized without ETTR because there is not enough information to provide smooth tonal transitions so far to the left on the histogram. This is well explained in Michael's tutorial on the subject and verified from experience. It's correct most of the time.

ETTR exposures can look like crap in ACR, but I find the adjustments are usually quite straight-forward for a wide variety of images:

(1) If there is a bit of clipping, use Exposure to rescue some tonality, unless it is specular highlights which are often best left ignored;
(2) Use the linear version of Curves in ACR to bring out contrast by dragging the upper and lower end points of the curve to their corresponding end points of the histogram without clipping anything.
(3) If need be, go back to Adjust and tweak the brightness slider to improve the mid-tones.
(4) Check for CA, etc., then convert.
(5) If saturation still needs a boost, fix it in PS with an HSB Adjustment Layer or a Selective Color Adjustment Layer. The effect can be limited to a certain colour range, or using a layer mask limited to certain parts of the image.

Another way of improving the vibrancy of really flat images is before doing anything else, convert them to Lab and steepen the A and B curves insuring that they always pass through the center point of the matrix. But do it carefully - these are highly leveraged adjustments. The optimal way of doing this is to duplicate the background layer, add a Curves Adjustment layer with clipping path linked to the duplicated layer, adjust A and B, merge the two layers, then re-convert to RGB without flattening. This way you can adjust the strength of the new "Lab layer"  in RGB mode by altering its opacity to taste. The reason for this procedure is that Adjustment Layers cannot survive mode changes between colour working spaces.
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thierrylegros396

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« Reply #26 on: October 07, 2006, 02:39:35 am »

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+1 saturation is going to cause saturated colors to blow out in the review/histogram much faster than the RAW.
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+1 saturation is to compensate for desaturation due to minimum contrast !!!
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John Sheehy

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« Reply #27 on: October 07, 2006, 09:39:59 am »

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+1 saturation is to compensate for desaturation due to minimum contrast !!!
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General saturation affects all tonal ranges, though.

The saturation setting in the camera only affects the camera's conversion, or an external conversion, if it honors the file's defaults.

In-camera saturation settings have no effect on RAW capture.  RAW capture always has the same saturation, at all levels except as affected by noise in the shadows, or hard-clipping or non-linearities in the highlights.  The second-lowest ISO any camera can do is pretty much guaranteed not to have non-linear RAW highlights.  It is usually only the lowest ISO that has non-linear highlights (if the camera has them at all).
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TimothyFarrar

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« Reply #28 on: October 11, 2006, 01:50:04 pm »

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Unfortunately, popular converters like ACR provide no way for the user to simply scale the exposure before the rest of the conversion.

John, doesn't the exposure slider in ACR linearly scale the exposure (in contrast to the brightness slider which applies a non-clipping curve)?
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Timothy Farrar
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TimothyFarrar

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« Reply #29 on: October 11, 2006, 02:13:07 pm »

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1. When would I use the expose to the right theory?
2. If i'm going to use this theory, is it not better rather to take multiple exposures and then digitally blend them?
3. What is the diffence btw the two methods?
4. Can they be used together ?

My two cents,

ETTR when taking a shot involving action (ie sports), otherwise bracket and digitaly blend. You can effectively remove all noise in a digital capture (even when appling a graduated neutral density filter digitally) by blending 5 to 7 exposures spaced 1 stop apart starting with the proper (non-clipping exposure) and overexposing. Larger exposure spacing and blending less exposures will result more noise, example below,

http://www.farrarfocus.com/ffdd/blog20060926.htm

I've found for landscapes, bracketing can faster then metering and checking for proper exposure or the right amount of ETTR.
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Timothy Farrar
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Jonathan Wienke

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« Reply #30 on: October 18, 2006, 09:34:50 am »

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I've seen plenty of images I've taken that are exposed to the left and they are superior to those I exposed to the right. This is because the exposure is the camera's best guess for the scene. It is many times fooled into over or underexposing and only your LCD can show you that. The histogram will not guide you because it will look like the exposure is dead on, and then be visually blown out on the LCD.

If you are seriously proposing that the appearance of the image on the little non-color-managed LCD on the back of the camera is a more reliable indicator of proper exposure than the histogram, you are sadly mistaken.

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Also, if you expose to the right, you can lose color saturation that RAW processing will not recover. So this ideas in theory is correct because it helps the sensor capture more detail in the shadows, but in practice, it can play havoc with your images.

As an example, I shoot many dusk and night shots, and I almost never get a nice, accurate exposure reading from my 20D or  nor now my 5D unless I use something like center weighted, aim for the most average brightness of the scene, and have a gradual light to dark transition in the scene--something like taking a picture of a boat and it's mast about 10 minutes after sunset. But then if I expose to the right, I lose color saturation, although I may save detail in the shadows.

This is utter balderdash. If you're "losing color saturation" you are either overexposing and clipping at least one color channel, or adjusting image brightness in Photoshop instead of using the exposure control in the RAW converter, or doing something else wrong. I've shot over 120,000 frames with digital cameras, and I have yet to find a situation where a frame with less exposure was superior to a frame with more exposure, unless the frame with more exposure had clipping.
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dwdallam

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« Reply #31 on: November 17, 2006, 05:00:51 am »

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If you are seriously proposing that the appearance of the image on the little non-color-managed LCD on the back of the camera is a more reliable indicator of proper exposure than the histogram, you are sadly mistaken.
This is utter balderdash. If you're "losing color saturation" you are either overexposing and clipping at least one color channel, or adjusting image brightness in Photoshop instead of using the exposure control in the RAW converter, or doing something else wrong. I've shot over 120,000 frames with digital cameras, and I have yet to find a situation where a frame with less exposure was superior to a frame with more exposure, unless the frame with more exposure had clipping.
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If you had read the previous replies, you'd understand that I meant yes, if you expose too much to the right, you can lose information from over exposing. And this can pose a problem is you rely on your histogram in high contrast settings.

It is only my experience that my histogram is unaccurate in many high contrast instances, either under or over exposing as shown comparatively in the LCD. Is the LCD more accurate than the histogram--I'm not interested in that argument because there are too many variables to account for and definitions to go voer before we can even start. Also, I can fix the problem using exposure comp and bracketing.  But when I see a nearly black LCD image--except for the sunlight clouds--and the histogram shows a "correct" exposure, then I know it's lying--period.

I don't know what else to say on that subject except that my eyes may be very bad, or my camera is broken and will not expose corectly in high contrast situations.
« Last Edit: November 17, 2006, 05:02:46 am by dwdallam »
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Jonathan Wienke

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« Reply #32 on: November 20, 2006, 07:12:59 am »

More likely, your camera is set in such a way that the histogram isn't as useful as it might be. Read this article and tweak your camera settings and do the test under "Using The Histogram To Properly Judge Exposure". It may help your camera histogram be more useful to you.
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dwdallam

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« Reply #33 on: November 21, 2006, 04:05:36 am »

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More likely, your camera is set in such a way that the histogram isn't as useful as it might be. Read this article and tweak your camera settings and do the test under "Using The Histogram To Properly Judge Exposure". It may help your camera histogram be more useful to you.
[a href=\"index.php?act=findpost&pid=86146\"][{POST_SNAPBACK}][/a]

Going there now. Thanks for the link.

OK, I have some questions for you. The article says, "I recommend setting contrast to its minimum value. . . ." Does this mean set it to negative numbers, or just 0?

I have all my jpg settings at faithful, which is 0 all the way across.
« Last Edit: November 21, 2006, 04:15:06 am by dwdallam »
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thierrylegros396

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« Reply #34 on: November 21, 2006, 06:18:50 am »

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Going there now. Thanks for the link.

OK, I have some questions for you. The article says, "I recommend setting contrast to its minimum value. . . ." Does this mean set it to negative numbers, or just 0?

I have all my jpg settings at faithful, which is 0 all the way across.
[a href=\"index.php?act=findpost&pid=86319\"][{POST_SNAPBACK}][/a]


I think it is minimum possible value, it depends of your camera firmware.

Some have negative number, other scale from 0.

Thierry
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BernardLanguillier

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« Reply #35 on: November 21, 2006, 08:55:14 am »

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That should have been on the very first digital to offer RAW output.  I'm still waiting.  These manufacturers play us for idiots.
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The problem is complicated by the fact that WB will change the blown status of the channels, won't it?

To be able to use a RAW histogram in the field fully would implicely require us to think about WB at that time... if we don't, then it won't be much more accurate than a jpg based histogram... but we like RAW because we think that we can forget about WB in the field... argh... :-)

OK, AWB used as a base for RAW histogram would probably be a good approximation...

Regards,
Bernard

Mark D Segal

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« Reply #36 on: November 21, 2006, 09:14:12 am »

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The problem is complicated by the fact that WB will change the blown status of the channels, won't it?

To be able to use a RAW histogram in the field fully would implicely require us to think about WB at that time... if we don't, then it won't be much more accurate than a jpg based histogram... but we like RAW because we think that we can forget about WB in the field... argh... :-)

OK, AWB used as a base for RAW histogram would probably be a good approximation...

Regards,
Bernard
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Bernard, I like to think - based on what I do when I remember - that WB when shooting RAW is essentially a non-issue. I carry both an ExpoDisc and a credit-card size Gretag COlor Checker. Snapping a frame with either one of them every couple of hours during a shoot, or whenever the lighting conditions change appreciably provides the data need to adjust all the photos taken around it. There doesn't need to be an issue about getting the "right" colour with this approach. The only remaining issue is whether that is the DESIRED colour, and at this point judgment intervenes over science. You can neutralize the warm glow of a snowy mountain at sunrise, but who would want to do that? At least RAW capture gives us the choice to be as mechanical or artistic as we wish.
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John Sheehy

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« Reply #37 on: November 21, 2006, 09:14:27 am »

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To be able to use a RAW histogram in the field fully would implicely require us to think about WB at that time...[a href=\"index.php?act=findpost&pid=86361\"][{POST_SNAPBACK}][/a]

Not at all.  Camera WB settings have no effect on RAW captures in most cameras.  A RAW RGB histogram would only tell you how you're exposing each channel.

For cameras that alter amplification per channel based on the WB setting, the data would still be useful, and can only help.
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Jonathan Wienke

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« Reply #38 on: November 21, 2006, 09:55:38 am »

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The problem is complicated by the fact that WB will change the blown status of the channels, won't it?

To be able to use a RAW histogram in the field fully would implicely require us to think about WB at that time... if we don't, then it won't be much more accurate than a jpg based histogram... but we like RAW because we think that we can forget about WB in the field... argh... :-)

Which is why I recommend using a fixed white balance that matches the JPEG-based histogram to the RAW data as closely as possible. A RAW histogram won't require you to worry about WB while shooting, it will simply accurately inform you which channel(s) are about to blow out.
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BernardLanguillier

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« Reply #39 on: November 21, 2006, 10:14:01 am »

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Which is why I recommend using a fixed white balance that matches the JPEG-based histogram to the RAW data as closely as possible. A RAW histogram won't require you to worry about WB while shooting, it will simply accurately inform you which channel(s) are about to blow out.
[a href=\"index.php?act=findpost&pid=86380\"][{POST_SNAPBACK}][/a]

Yep, you are correct, WB isn't an issue. My bad.

Regards,
Bernard
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