[Octave-bug-tracker] [bug #45779] Writing and 8-bit image to BMP produces a 24-bit bmp

[Ian Journeaux]

Follow-up Comment #3, bug #45779 (project octave):

I ran the following on my computer running win7 and Octave 4.1.0+.


imwrite (rand(100) > 0.6, "bool.bmp")
imwrite (randi ([0 255], 100, 100, "uint8"), gray (256), "with-gray-map.bmp")
imwrite (randi ([0 255], 100, 100, "uint8"), cubehelix (256),
"with-color-map.bmp")
imwrite (randi ([0 255], 100, 100, 3, "uint8"), "without-map-rgb.bmp")
imwrite (randi ([0 255], 100, 100, "uint8"), "without-map-gray.bmp")


After installing GraphicsMagick, gm returns


Depth: 1 bits-per-pixel component
Depth: 8 bits-per-pixel component
Depth: 8 bits-per-pixel component
Depth: 8 bits-per-pixel component
Depth: 8 bits-per-pixel component


respectively
So things might look correct. 

Unfortunately both Windows and ImageJ reports the last two Without-Map images
as 24bit. The size of the image files are also different. 
With-Map versions are 11kb while the Without-Map versions are 30kb.

 


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