Archive 2014 · Imaging Resource has a few 7DmkII samples up

snapsy
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p.5 #1 · p.5 #1 · Imaging Resource has a few 7DmkII samples up

alundeb wrote:
The clipped blacks represent a very minor part of the images in question. The difference in quality we see is in tones above the clipping level in the jpg. The histogram of the pushed jpg image has a smooth rolloff in the lower and, and even a small trail below that.

A histogram of a pushed JPEG will not show you the information that was clipped away from the original JPEG. Here is the +5EV raw again and I just did the same on the embedded JPEG from the raw:

+5EV raw
+5EV embedded JPEG from raw

Notice the detail/tone lost from the pushed JPEG compared to the raw.

Sep 18, 2014 at 10:03 AM

alundeb
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p.5 #2 · p.5 #2 · Imaging Resource has a few 7DmkII samples up

snapsy wrote:
A histogram of a pushed JPEG will not show you the information that was clipped away from the original JPEG. Here is the +5EV raw again and I just did the same on the embedded JPEG from the raw:

+5EV raw
+5EV embedded JPEG from raw

Notice the detail/tone lost from the pushed JPEG compared to the raw.

We can't see clipped information, but we can see from the histogram of a pushed image if there were clipped blacks. If there were clipped blacks, therer would be a peak or "wall" at the left end of the histogram, with the previous black now represented as grey. It would be a sharp peak with nothing below it.

Anyway, here is the histogram of the original jpg. It does not contain clipped blacks, ok?

http://i306.photobucket.com/albums/nn242/Overflate/histogram_jpg_zps3534808b.jpg

Sep 18, 2014 at 10:35 AM

snapsy
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p.5 #3 · p.5 #3 · Imaging Resource has a few 7DmkII samples up

alundeb wrote:
We can't see clipped information, but we can see from the histogram of a pushed image if there were clipped blacks. If there were clipped blacks, therer would be a peak or "wall" at the left end of the histogram, with the previous black now represented as grey. It would be a sharp peak with nothing below it.

Anyway, here is the histogram of the original jpg. It does not contain clipped blacks, ok?

http://i306.photobucket.com/albums/nn242/Overflate/histogram_jpg_zps3534808b.jpg

Clipped blacks refers to what tonal information was clipped for the rendered image relative to the original image. This can't be determined by looking at the histogram of a JPEG image because the JPEG is the result of a gamma curve applied to the raw data.

Sep 18, 2014 at 10:41 AM

alundeb
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p.5 #4 · p.5 #4 · Imaging Resource has a few 7DmkII samples up

snapsy wrote:
Clipped blacks refers to what tonal information was clipped for the rendered image relative to the original image. This can't be determined by looking at the histogram of a JPEG image because the JPEG is the result of a gamma curve applied to the raw data.

Yes it can. If clipping occurs, the clipped values are assigned the minimum value that can be represented. All the clipped pixels are assigned the same value, and you see those as a sharp "wall" in the left end of the histogram. The gamma curve only moves the position of this "wall"

Sep 18, 2014 at 10:51 AM

snapsy
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p.5 #5 · p.5 #5 · Imaging Resource has a few 7DmkII samples up

alundeb wrote:
Yes it can. If clipping occurs, the clipped values are assigned the minimum value that can be represented. All the clipped pixels are assigned the same value, and you see those as a sharp "wall" in the left end of the histogram. The gamma curve only moves the position of this "wall"

The gamma/tone curve can move the wall so that there's a gap at the left edge of the histogram. Whether it actually does so depends on which gamma/tone curve is being applied, including "value add" features that camera firmware use to tweak the conversion, such as adaptive DR techniques.

Sep 18, 2014 at 11:05 AM

alundeb
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p.5 #6 · p.5 #6 · Imaging Resource has a few 7DmkII samples up

Here is a histogram with clipped blacks

http://i306.photobucket.com/albums/nn242/Overflate/histogram_clipped_jpg_zps40da757b.jpg

And the image in question

http://i306.photobucket.com/albums/nn242/Overflate/histogram_jpg_zps3534808b.jpg

Sep 18, 2014 at 11:06 AM

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