2013.03.26 12:26 "[Tiff] The ITU T.24 test images", by Steve Underwood

Hi,

I am trying to use the ITU T.24 TIFF test images/files, and I have found what appear to be some errors in the files. I am hoping someone here might be able to confirm what I have found, or tell me I've done something stupid.

The images F01_*.TIF to F16_800.TIF have the photometric tag set to min-is-black, when it appears they should be set to min-is-white, since that seems to be how the images are compressed.

The images F18_200.TIF and F18_400.TIF have the photometric tag set to min-is-black, and this makes them agree with the images in the PDF files that accompanies the image files. However, this gives them a black background, which doesn't look right. If I change the photometric to min-is-white the images don't agree with the PDF file, but they look much more sane.

The image INGRES16.TIF is supposed to be a 12 bit deep colour image, but it tagged as 16 bit, and has 16 values for R, G and B. However, the contents of these 16 bit values only fill the low 12 bits, and the image displays as almost black. If I repack the values shifted up 4 bits the image looks fine. libtiff says there are lots of bad tags in this file, but this appears to be harmless.

Regards,
Steve