Gray(scale) image with a colormap - how to turn into double?
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John Kau
on 30 Jul 2015
Commented: MatlabEnthusiast
on 22 Dec 2019
Hi,
I have an 8-bit image that consists only of gray colors. On checking the characteristics of the image in Matlab with imfinfo, it turns out that it is ColorType "indexed" and has a colormap of 256x3. I would like to transform this image into a simple grayscale image of a n x m matrix (according to its size) class double.
The function ind2gray demands a colormap and using the colormap of this image didn't work on my end. Probably I'm doing something wrong.
Any help is much appreciated.
I'm struggling finding a solution.
Thanks
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Accepted Answer
David Young
on 30 Jul 2015
Edited: David Young
on 30 Jul 2015
This works OK:
[imInd, cmap] = imread('10.bmp');
imGrayUint8 = ind2gray(imInd, cmap);
imGrayDouble = im2double(imGrayUint8);
imshow(imGrayDouble);
3 Comments
Image Analyst
on 31 Jul 2015
What did you do when you said "The function ind2gray demands a colormap and using the colormap of this image didn't work on my end"? Because that is exactly what David did. And casting to double shouldn't really be necessary.
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