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November 2000
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2000.11.21 00:44 "Re: Outstanding Libtiff Issues", by Joris Van Damme
Frank Warmerdam wrote: > 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