[Octave-bug-tracker] [bug #45565] Using imwrite to write an 8-bit iamge to BMP creates a 24 bit image

[Mike Miller]

Update of bug #45565 (project octave):

                Category:                    None => Octave Function        
                  Status:                    None => Works For Me           
        Operating System:       Microsoft Windows => Any                    

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Follow-up Comment #2:

Thanks for your bug report. AFAICT this is working correctly. If I understand
the BMP file format correctly, 8-bit BMP files are indexed images. To create
an indexed image with imwrite, you must specific a colormap (palette)
argument.

For example, this creates an 8-bit BMP file for me:


octave:1> img = uint8 (ones (100, 1) .* [0:255]);
octave:2> map = rainbow (256);
octave:3> imwrite (img, map, "foo.bmp");


Am I understanding this correctly?

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