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16bit/ch tiff inferiror to 8bit in Elements?

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Old 08-31-2003, 03:36 AM
Julio Julio is offline
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16bit/ch tiff inferiror to 8bit in Elements?

Hi folks, first post in this forum.

I'm trying to absorb quite a bit at the moment. After many years of scanning negatives into my computer and using my old trusty Canon A-10 digital for snapshots, I have recently purchased a Canon 10D. It came with Elements II and after a bit of fooling around with the program, I decided to get serious with it and started working my way through the Hidden Elements book (I'm sure I'll be posting in that forum as well in the near future.)

The Canon 10D uses as it's maximum quality setting a RAW format that has to be decoded and transferred to JPEG or TIFF through a Raw convertion utility (I'm using the included Canon File Viewer) I have lot's of memory and horsepower in my computer so when I convert and transfer the file to elements I'm trying to do so using maximum quality.

The Canon software manual leads me to believe that when I go from Raw to Tiff, it's preferable to do "linear" processing on the file. It specifically tells me that it minimizes "...the image degradation that normally accompanies tone curve adjustment..." This option only works however, if I convert the Raw image to a 16 bit/chanel tiff. If I try to use this 16 bit tiff in Elements it tells me that it is an unsupported format and converts it to (an 8 bit/ch tiff I assume) something.

The problem is that if I convert the same RAW to 8bit/ch and 16bit/ch and open them both in Elements, the alledgedly inferior 8bit version looks much better - the 16bit version looks badly underexposed and oversaturated - my visual appraisal is also confirmed by comparing the 2 vastly different histograms.

What's going on here? Can someone explain why this should be so?

(I am also posting this in the Canon 10D forum at Digital Photography Review - my apologies for the redundancy to those of you who also frequent that site)
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Old 09-01-2003, 09:56 AM
Richard_Lynch's Avatar
Richard_Lynch Richard_Lynch is offline
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I am not sure where you suggest the problem is occurring. As you can't open the 16 bit images in elements (without converting) how are you looking at unconverted results?

Your color management settings will play into this as will image views/previews. I haven't experimented with this directly. can you give a more linear description as to how you are handling the files and post a comparison of the image results?
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Old 09-01-2003, 01:39 PM
Julio Julio is offline
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Thanks for the reply, Richard.

I believe the problem is occuring in one of 2 places:

1. The Canon utility that uses linear conversion to produce 16 bit/ch is faulty (this has been suggested to me by someone at Digital Photography Review) or;

2. Element's conversion of 16 bit/ch tiffs to 8 bit/ch is faulty.

I do understand that Elements does not support 16 bit tiffs and that's fine. I'm just trying to send to Elements the best quality image before I start making adjustments there.

I was trying to send elements the same unretouched image using the 16 bit and 8 bit conversions in the Canon utility to try to determine which had better shadow detail. I wasn't expecting the result I saw.
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Old 09-01-2003, 06:30 PM
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Kevin Connery Kevin Connery is offline
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The FVU and earlier RIC both offered gamma-corrected or linear conversions. In linear mode, the images will look very dark and low in saturation--perhaps looking 2-4 stops underexposed. That's to be expected in a linear RGB color space.

To get it into a usable color space (sRGB, Adobe RGB, Colormatch, whatever), you need to follow-up with some processing. The Canon software does NOT include that; if you want straight-forward conversions, don't use the linear approach. (Also don't use Linear except in 16-bit mode; there's too much risk of posterization to make it a safe practice [though it can work in some limited cases].)

I used Canon's RIC (predecessor to the FVU) for a few months before Adobe shipped their Adobe Camera Raw plug-in, and used it in Linear; the results were very good--after running a long action to tune the gamma and color saturation.

If Elements won't import/open 16-bit tiff files, I do NOT recommend using linear mode for your RAW conversion. (And you may want to consider looking into BreezeBrowser (PC only), Adobe's Camera Raw plug-in ($100), or PhaseOne's CaptureOne dSLR ($100 for limited edition, $500 for full); they're well-respected RAW converters for Canon cameras.) Or just use the FVU and convert to the best 8-bits you can using FVU itself; it's not at all bad. (Just slow.)

ALL of those approaches should give you better results than trying to deal with a linear file in 8-bit mode.
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Old 09-01-2003, 08:46 PM
Julio Julio is offline
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Thank you Kevin. That explains quite a bit

I actually downloaded and started using the trial version of CaptureOne dSLR LE yesterday - it seems great and definitely much faster than the Canon utility.

I am also happy with the FVU output in 8 bit tiff mode... the 16 bit experiment just had me a bit confused.
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