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Author Topic: C2P  (Read 4606 times)
Tim Gray
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« on: August 04, 2007, 08:21:28 AM »
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First, there was a passing reference in one of the chapters to "linearizing" the printer, and there's also a short discussion on this in Mastering B&W Printing by Diallo (HIGHLY recommended - I was about half way through when I saw Michael recommend it in the  "Books" chapter on the video).  In any event, it sounds like it precedes the creation of the printer profile - but I haven't run across this concept before.  Any more info as to what this is all about?

2nd - the addition of 2 more "bits" to  the 1d3 raw files adds significantly to the space available to adjust shadows.  At some point increased bit depth should make ETTR largely unnecessary.  At 14 are we there?  

I have to say that the 6+ hours just flew - 2 thumbs up!!

A bit off topic, but I've had a 1d3 for about a week, and while the official position from Canon is that the dynamic range is basically unchanged (if I recall their white paper correctly), I'm seeing more latitude in digging detail out of the shadows and highlights.  This is  probably just the result of the higher bit depth - but it "looks" like better DR.  I know the histogram is based on jpg, but I'm seeing that it's even less useful for predicting "true" clipping than it was with the 1d2.  

I'm off to Montreal for three days, so I'll check this thread when I'm back...    To those of us who are so lucky - have a great long weekend!
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jani
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« Reply #1 on: November 13, 2007, 09:21:16 AM »
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I'm only about 100 days behind! Not bad!

Apparently, noone else has answered this one nor posted again about ETTR, so I'll give it a shot.

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2nd - the addition of 2 more "bits" to  the 1d3 raw files adds significantly to the space available to adjust shadows.  At some point increased bit depth should make ETTR largely unnecessary.  At 14 are we there? 
I don't see how all the bits in the world will make it unnecessary to follow the ETTR doctrine. If a highlight is blown, it's blown because you've over-exposed beyond the sensor's limits.

What a higher bit depth can give you, however, is the headroom to encode a higher dynamic range, or the same dynamic range with smoother gradients.

Ideally speaking, though, you wouldn't have a bit depth at all.
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Jan
Mark D Segal
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« Reply #2 on: November 14, 2007, 01:41:27 PM »
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I don't think we can know without tetsing whether higher bit depth makes it less useful to ETTR. The idea of ETTR is to capture as much of the available photons as possible without blowing highlights. Prersumably more information is always better than less, but at what bit-depth it ceases to have practical signfigance I think remains to be seen.
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Mark D Segal (formerly MarkDS)
Author: "Scanning Workflows with SilverFast 8....." http://www.luminous-landscape.com/reviews/film/scanning_workflows_with_silverfast_8.shtml
jani
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« Reply #3 on: November 15, 2007, 07:44:57 AM »
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I don't think we can know without tetsing whether higher bit depth makes it less useful to ETTR. The idea of ETTR is to capture as much of the available photons as possible without blowing highlights. Prersumably more information is always better than less, but at what bit-depth it ceases to have practical signfigance I think remains to be seen.
The bit depth doesn't have much to do with blown highlights or not, as the bit depth is part of the process after the A/D conversion.

For instance, the best A/D conversion for audio is currently a 1-bit process, but the volume may still clip above the useful sensitivity of the recording equipment in the analog process. The resulting audio files may be 16-bit, 18-bit or 128-bit for all the world cares; the audio is still clipped.

There is no reason why a higher bit depth should be a magic bullet for photographic sensors, when it isn't in other applications.
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Jan
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