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March 2006
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2006.03.26 23:48 "Re: 3.8.1 and JPEG problem", by Mikhail Kruk
> > The snapshot I have doesn't read or write JPEG TIFFs (output is all > > black)... I'm testing using tiffcp, is it possible that the problem is > > with it, not the lib? Reading JPG works fine with my own program I > > build against 3.8.0. Do you want me to try linking my app with the > > CVS snapshot? > > I also tried tiffcp from 3.8.0 and it doesn't work. > > I guess the next logical step is to assume that tiffcp is broken and > > test with my app, but I want to make sure that I'm looking at the > > right CVS since you sound like you've made some changes and I don't > > see them. > > I've not tested tiffcp, but the results you were getting make perfect > sense with the bugs I've corrected in several other files, so I would > assume there's nothing wrong with tiffcp as such. It may *seem* that way > though... There are several ways to access JPEG compression in TIFF, and > only the recommendable way, without use of the pseudotag JPEGCOLORMODE, > was broken (as far as I know). So, one app may have been suffering, > while another may have been behaving perfectly OK. > > When I update CVS, I see what I have comitted. Frank was waiting for the > bugfixes, so I assume he too, will soon update CVS and check out my > fixes. Since I know very little about CVS systems beyond there basic > use, all I can suggest at this stage is > - wait a couple of hours maybe, and check again? > - wait for Frank to report back? > - check the changelog file in the root level. The top few entries should > read the following: All right, I got the CVS problem partly figured out. I don't understand why diff wasn't showing any differences, but a new checkout gave me all your changes. I tested again using tiffcp. The only TIFF file which is JPEG-compressed I have is in YCBCR color space. tiffcp didn't process it correctly, I believe there is a bug in it, but when I brute forced it to do TIFFSetField(in, TIFFTAG_JPEGCOLORMODE, JPEGCOLORMODE_RGB); it worked (tiffcp -none jpg.tiff out.tiff produced an unencoded image which looks correctly). Don't have time to compe up with correct tiffcp patch right now). I then tried encoding a regular (packbits) TIFF into JPEG (tiffcp -c jpeg test.tiff jpg.tiff) and the result shows up as black in the viewer (the same viewer shows my original YCBCR-encoded file normally, so it knows how to do JPEG; the viewer is Microsoft OFfice Document Imaging, it's pretty good, I've managed to confuse it only once with a 100x20 file which had DPI of 100 specified in it, but I digress). I then used tiffcp to convert that black image back to unencoded and got a good result.