Not-so-lossless conversion from .NEF to .TIFF in Capture NX2
I noticed today some strange - and possibly, bad - behavior in Capture NX2. When I try to save my .NEF files into 16-bit TIFF files, it seems that I loose level depth information that I should not loose. Of course, I am not considering any "para-picture" information included in the NEF that are not included in TIFF, like ADL, Picture control, or whatever; I am talking about simple image information, with 12-bit depth in .NEF files, and .TIFF files with 16-bit depth. I need to do this conversion for treatment with third party software.
If I do the next sequence of event, it seems that I detect a bug:
- Open a .NEF file in which you have clipped contents in the highlights when opening it (a over-exposed sky with clouds, for instance).
- Save it in .TIFF format, one 16-bit, one 8-bit. (no compression)
- Close all files
- Open all files
- Go in the "Quick Fix" panel, and push the highlight protection to the max for each file
- Watch the result.
- The highlight protection in the NEF file has created some beautiful rendition of stuff you could even not know they were there before; that's the magic of RAW format and edition.
- Nothing like that happen in the .TIFF 16-bit file, it gives a very bad result with all clipped still clipped, as it would appear from a on-camera silly JPEG.
- Editing the 8-bit file give the exact same result (but this is normal).
ADDITIONAL Remarks :
- It gives the same conclusion if you open and edit (Highlights to min, exposure down...) the three files in LightRoom. (Steps 4 to 6 above)
- Opening a tiff prevents NX2 to compensate the exposition (gray level).
- [Different subject : Enabling LZW compression don't change anything (of course...). Strange : it halves the size of the file when using View NX2, while it increases it with Capure NX2 !!]
So.... What's happening? Three hypotheses :
- (a) the 16-bit TIFF is actually not lossless compared to the .NEF (and again just regarding the image information...). Could Capture NX2 really crop the depth to 8 bit even from 12-bit .NEF to 16-bit .TIFF ??
- (b) both Capture NX2 and LR cannot properly handle 16-bit edition of files.
- (c) Something linked to my configuration (Win7 64, intel I5, 8gb RAM) prevents me to do it properly
Could anyone reproduce the bug, and or try to edit and compare the three files with another software? I'm kinda astonished right now... This totally kills the power of .TIFF files as a mean to pass and store the files in a lossless, RAW-like format.
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|Jan 12, 2013|
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