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Author Topic: 16 Bit TIFF in MFDB workflow?  (Read 6733 times)
Jonathan Wienke
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« Reply #20 on: January 04, 2007, 07:36:54 AM »
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Thanks, Jonathan,  for your demo

but I think that's the case of linear conversion.
CaptureOne's linear conversion appears to be much brighter than other raw converter's. So there are no that much detail compressed into the shadow.

Here is a comparison, a steep curve applied...

i don't see a substantial difference between 16b and 8b version.

That's because you're applying the curve internally in Capture One (which is always in 16-bit mode), and then downsampling to 8-bit after the curve is applied. Your test is not valid. Export the dark image into Photoshop, convert to 8-bit mode, then apply the curve, and you'll get something much different.
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makercob
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« Reply #21 on: January 06, 2007, 04:02:53 AM »
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That's because you're applying the curve internally in Capture One (which is always in 16-bit mode), and then downsampling to 8-bit after the curve is applied. Your test is not valid. Export the dark image into Photoshop, convert to 8-bit mode, then apply the curve, and you'll get something much different.
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i said, for twice, the curve was applied in photoshop.

the question is:
there is huge difference between 16b and 8b images' histogramafter a very steep curve, the 8b image's histogram did turn very discrete whereas the 16b image's histogram remained continuous.

BUT why there is no such obvious difference when comparing the images, on an Apple Cinema Display HD.

there is nearly no difference in shadow
a little bit more in mid-tone, and finally gets a little bit obvious in hightlight

maybe PhaseOne's lossless compression is in fact not lossless
maybe 16 bit images only depict CCD noise more smoothly than 8 bit ones for this generation of MFDB. (that's why the histogram is smoother but the image is not)
« Last Edit: January 06, 2007, 04:06:39 AM by makercob » Logged
Graham Mitchell
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« Reply #22 on: January 06, 2007, 05:02:08 AM »
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I think you are doing something wrong in your workflow. Jonathan's sample makes the difference very clear. 16-bit is very important is you are going to be applying curves.

Try it for yourself.

I just downloaded the file from http://www.visual-vacations.com/Photograph...2-0021_RT16.TIF

Here are my results using the same curve, first in 16 bit then in 8 bit





See the poor quality of the 8-bit version?
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Graham Mitchell - www.graham-mitchell.com
Jonathan Wienke
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« Reply #23 on: January 06, 2007, 09:25:26 AM »
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Perhaps the problem is that your sample image is extremely noisy to begin with, so posterization isn't as noticeable because it's masked by the high noise level. But if you use a clean image, gradient posterization is a lot more noticeable.
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John Sheehy
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« Reply #24 on: January 06, 2007, 09:26:32 AM »
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maybe PhaseOne's lossless compression is in fact not lossless
maybe 16 bit images only depict CCD noise more smoothly than 8 bit ones for this generation of MFDB. (that's why the histogram is smoother but the image is not)
[a href=\"index.php?act=findpost&pid=94049\"][{POST_SNAPBACK}][/a]

If it is showing *sensor* noise more accurately, then it is also showing the image more accurately, because sensor noise *is* signal, and only called noise because it is generally unwanted.  If the act digitizing at 16 bits, however, is the cause of more read noise in the more significant bits, then it is counter-productive.
« Last Edit: January 06, 2007, 09:27:29 AM by John Sheehy » Logged
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