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<div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;">I have recently started having to work with big multi-image tiff files, e.g. 4.5 GB. I discovered that ITK on Windows cannot handle such large images, so I am trying to use Linux
(64-bit ubuntu 12.10). I managed to build ITK with libtiff5 (actually 4.0.2 I think) which does have bigtiff support, after downloading the latest source code with git, which contains a patch fix for a bug that prevented building. The patch was applied yesterday,
so that was a bit of luck.<br>
<br>
But there is something screwy happening when I read my multi-image tiff with ITK. After reading the image (which is compressed with Deflate) I look at each z-frame and compute the sum of pixel intensities. After z=346 all the intensities are 0, but I know
this is not correct. I can view the frames with Imagemagick's display program, and those at z>346 are not qualitatively different from the earlier ones.<br>
<br>
After reading the image in I am using a pointer to the buffer to access the data:<br>
<br>
p = (unsigned char *)(im->GetBufferPointer());<br>
<br>
then I access the voxel value at (x,y,z) as p[z*xysize+y*width+x]<br>
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I have declared x, y, z, width and xysize = width*height all as long int.<br>
<br>
Another way to show the problem: When the compressed tiff that looks correct when viewed with Imagemagick-display is read with ITK and then written without compression, the uncompressed version has blank frames for z>346. This tiff has 693 frames, each 601x1380.
Exactly the same thing is seen with another tiff that has 693 frames each 779x1380 - again the uncompressed version is blank after frame 346.<br>
<br>
I'd be interested to know if anyone else is reading big tiffs with ITK, on Linux.<br>
<br>
Thanks<br>
Gib</div>
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