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May 2004
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2004.05.07 16:37 "Tiff questions", by James Carroll
Hi, I have a bunch of questions. I am exploring using TIFF support for my image server that also supports FlashPIX. The general idea is that the images are very large, and people want to zoom in and out, so I am trying (pyramidal) multiple levels of downsampled versions of the same image, all stored as jpeg-compressed tiles. I notice Adobe Photoshop can save a pyramidal TIFF, but when I do so, then look at it with tiffinfo, I don't see multiple pages, or tiles. It seems to be one large image. The file size is 4x what the image would be normally, so something extra is stored somewhere. Normally the image pyramid makes the file 1.33x bigger (not 4x.) Something tells me this isn't going to help me. Can anyone point me to the details of the Photoshop Pyramidal format? I've got a small test program using libtiff that I'm using to test writing tiled tiffs, and it fails. I get a strange return code from the write, but haven't found a reference of what the return values mean. I notice there's an TIFFErrorHandler callback I can register, but I can't find any examples or specifics of how to do this. Maybe this would tell me what I'm doing wrong. How do I make sense of the return codes when writes fail using libtiff? When I write tiff tiles, there are parameters for x, y, and z. Does the Z parameter correspond to different pages in a multi-tiff or is it a different mechanism? (Please CC: jim@microbrightfield.com, I'm trying to subscribe, but my subscrption is deferred for approval.) Thanks! -Jim Carroll