1994.04.07 14:05 "", by Christoph Wissing

1994.04.07 14:05 "", by Christoph Wissing


At first congratulations to your good software, the libtiff. I`m using it within my "Diplomarbeit" for reading and writing pictures.

I encountered a problem when reading some grayscale X-Ray-Images: They use 6 Bit per Sample, and I`ve seen in your doc`s:

    o Class G for grayscale images
        SamplesPerPixel = 1
        BitsPerSample = 4, 8
        Compression = 1 (none) 5 (LZW)
        PhotometricInterpretation = 0 (Min-is-White), 1 (Min-is-Black)

so they are not supported, in spite of that palette color images with 6 Bit are. I`ve proven that, when loading such a picture with the libtiff, the pictures are nearly completely black, but not useable.

Are there plans to extend the libtiff to read 6 Bit graylevel images, or should I try to work it into the libtiff? Or do I misunderstand something? I`m using the libtiff version 3.2 on a Sun, a Linux PC, an SGI, and an SCO-Unix PC and on my Atari Falcon: No where a problem with other pictures, only these 6 Bit Bastards don`t work.

Have you any suggestions?

Of course I could send you such an 6 Bit (uncompressed!) Picture, if you want. But, of course, I doon don`t want to steal your time, only please let me know whether I should do a workaround by myself, or I`ve misunderstood something, or in the near future there is support for 6Bit Grayscales.

With many greetings,