2006.03.27 04:54 "Re: [Tiff] 3.8.1 and JPEG problem", by Joris Van Damme

Mikhail,

Using TIFFTAG_JPEGCOLORMODE in tiffcp is no option as far as I'm concerned, the bug ought to be fixed instead of burried under bad logic.

No, I think it's the right solution for my decoding problem.

I disagree.

tiffcp -c jpeg:r moon.tif jpg.tif moon.tif is at http://www.scorch2000.com/~meshko/moon.tif jpg.tif is at http://www.scorch2000.com/~meshko/jpg.tif

I can't download moon.tif.

jpeg.tif is a perfectly fine file, in my opinion. It is weird, in that it contains RGB instead of the much more common YCbCr. That's weird and uncommon, but it is valid. It is also weird in that it contains an YCbCrSubsampling tag. That is weird, but correct reader behaviour is to not care about that tag, since the Photometric does not allow any subsampling.

Since I can't download moon.tif, I can't compare, but jpeg.tif colors seem not at all out of the ordinary, not at all like I'd expect when YCbCr is contained and interpreted as RGB, or the other way around, at any stage in your process.

The 'r' option after 'jpeg:r', seems to be intended to force output color image as RGB rather than YCbCr. So if you want a more common JPEG-in-TIFF, presumably, should you not use 'tiffcp -c jpeg moon.tif jpg.tif' instead?

Again, the wierd thing is that running tiffcp -c none jpg.tif out.tif produces correct file, so somehow the image is correctly stored in jpg.tif, it's just not viewable in the TIFF viewer which does support JPG-encoded TIFFs.

This finding supports my opinion on jpg.tif. The 'TIFF viewer which does support JPG-encoded TIFFs', does not support and display correctly this particular weird JPEG-compressed TIFF. But that's not uncommon, almost any viewer out there is restricted in the number of flavors of TIFF that are correctly supported. Current CVS tif_getimage.c does support this particular weird JPEG-compressed TIFF file, and so does my own proprietary decoder.

Are you still seeing any of the warning or error messages that you reported before? Either with tiffcp usage, or with reading back any of the results with current CVS LibTiff, or any such?

Best regards,

Joris Van Damme
info@awaresystems.be
http://www.awaresystems.be/
Download your free TIFF tag viewer for windows here:
http://www.awaresystems.be/imaging/tiff/astifftagviewer.html