AWARE SYSTEMS
TIFF and LibTiff Mail List Archive

Thread

2000.11.13 15:37 "Outstanding Libtiff Issues", by Frank Warmerdam
2000.11.14 00:58 "Re: Outstanding Libtiff Issues", by Tom Lane
2000.11.21 00:44 "Re: Outstanding Libtiff Issues", by Joris Van Damme

2000.11.21 00:44 "Re: Outstanding Libtiff Issues", by Joris Van Damme

http://bugzilla.remotesensing.org/show_bug.cgi?id=23

http://www.ai.sri.com/cgi-bin/digitalearth/list.pl?dir=sfbay.oi

The images at the URL above, in varying resolutions, are all tiled YCbCr TIFFs with JPEG compression. Not all tools handle YCbCr TIFFs or tiled TIFFs (or both), so it would be nice if tiffcp did. But despite its lack of diagnostics, when run on such an image with only the -s option, tiffcp produces a tiny file with mangled Y, Cb and Cr components (at least judging by XV's output). For example, the 512x640 level-4 image shrinks from 240k to 33k and changes from a reasonable aerial shot (with black regions indicating no data) to a mostly teal image. Since the tiles are (reported to be) 128x128 pixels, it should be possible to losslessly convert such an image into strips of 512x128 pixels (or so I would imagine--I'm no TIFF expert).

I finally got my decoders up and running again, and I took a look at these images. Don't know about tiffcp (I don't use it), but, FWIW, I can tell you what the images look like in my LibTiff/LibJpeg compilation (I use current versions of both).

It seems they got an offset problem, and that the strips/tiles have been written individually upside-down. It's rather hard to give a good description, but I think that besides these two problems everything is ok, I can clearly recognize they are earth-pictures and LibTiff nor LibJpeg emits warnings or errors. If it's usefull to you, I could send you scaled-down bitmaps to take a look at (once I get my encoders up and running again), just pop the question.

Joris