2008.02.11 07:43 "[Tiff] TIFFReadRGBAImage rendering upside-down", by Mick O'Neill

2008.02.11 16:33 "[Tiff] Re: Help with TIFFWriteScanline()", by James Sumners

After browsing the mailing list archives I found out about the tiffinfo tool. tiffinfo reported that my original image had a SamplesPerPixel of 1. For some reason, unbeknownst to me, my program is getting a value of 0 for SamplesPerPixel from the original image. So I manually set the value to 8, because that is what I understand the specification to be (8 or 16 SPP for grayscale/color and 1 SPP for bilevel). After changing my manual SPP value from 8 to 1 the copied image is written correctly.

This is the first time I've done any graphics programming. So I'm sure that I am not understanding something. Would someone please explain this situation to me? Would 8 SPP squeeze the image into a smaller space? How is 1 SPP producing a grayscale image?

On Feb 11, 2008 10:52 AM, James Sumners <james.sumners@gmail.com> wrote:

I've written a program[1] that reads a grayscale image into memory and writes it to another file. The problem is that the new image is

multiple copies of the original image in the same pixel space. It's a bit difficult to describe. Included in the zip is "fractal_gs.tiff",

the original image, and "fractal_gs_2.tiff", the copy.

If I try to write the new image with TIFFWriteRawStrip() I get append errors. Using TIFFWriteScanline() I get an image, just not the one I

expect. What am I doing wrong?

[1] -- http://student.claytonstate.net/~jsumners/files/tiff_copy.zip

--
James Sumners
http://james.roomfullofmirrors.com/

"All governments suffer a recurring problem: Power attracts
pathological personalities. It is not that power corrupts but that it
is magnetic to the corruptible. Such people have a tendency to become
drunk on violence, a condition to which they are quickly addicted."

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CH:D 59