LibTiff Mailing List
TIFF and LibTiff Mailing List Archive
April 2005
Previous Thread
Next Thread
Previous by Thread
Next by Thread
Previous by Date
Next by Date
Contact
The TIFF Mailing List Homepage
This list is run by Frank Warmerdam
Archive maintained by AWare Systems
Thread
2005.05.02 18:43 "Re: Color TIFF/JPEG compression questions", by Joris Van Damme
Jason > So, I think that tiffinfo might be playing correctly here (since it > agrees with tiffdump, and I don't see any obvious problems with the > code.) We should check that we are talking about the exact same quad-jpeg.tif. I know for a fact that AsTiffTagViewer shows exactly what is there, and, unlike LibTiff, that stuff isn't burdoned with an actual image decoder part and a subsampling-fixup scheme and such... So if AsTiffTagViewer doesn't mention the tag, and tiffinfo does, I know for a fact that tiffinfo must be wrong. A newer version of AsTiffTagViewer that isn't published yet, also supports hex viewing of just about any structure in a TIFF file. With this version I was able to triple-check, and sure enough, the tag count of this IFD shows as 14 in a hex dump that is merely a hex dump and cannot possibly be wrong. 14 is the number of tags shown by both versions of AsTiffTagViewer. So tiffinfo *does* add the default or fixed-up or whatever values of YCbCrSubsampling even though the tag is *not* there. 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