I haven't looked at the code yet, but your theory sounds plausible to me. 


Michel Lerenard <[email protected]> wrote:
>Hi,
>
>There seem to be a bug in the BMP plugin. I've tried to write a single 
>channel file, using the following call:
>
>     ImageSpec spec(width, height, 1, TypeDesc::UINT8);
>     if(out->open("Test.bmp", spec)) {
>         success = out->write_image (TypeDesc::FLOAT, buffer);
>         out->close();
>     }
>
>and the resulting file seems to be corrupted. It does contains some 
>data, but the configuration is not correct:
>OIIO cannot reopen the image.
>GIMP sees a grayscale black image
>Photoshop sees a indexed color image, with an completely black color 
>table. Building a grayscale color table fixes the problem.
>
>The depth of the image is computed using:
>     m_dib_header.bpp = m_spec.nchannels << 3;
> From this page 
>(http://msdn.microsoft.com/en-us/library/windows/desktop/dd183386%28v=vs.85%29.aspx)
>
>I understand that 8bpp files (which is the case if I write only one 
>channel) must be palettized. "Bitmaps that are 1, 4, or 8 bpp must have
>
>a color table with a maximum size based on the bpp".
>
>So my guess is that the plugin should create a grayscale palette if 
>'nchannel' is equal to 1.
>
>Any thoughts ?
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-- 
Larry Gritz 
[email protected]
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