MATLAB: How to Store this attached rgbimage with a colormap. I tried the following code but could not write the image with colormap.

Question

I tried the following code to write the image with map. But again the colormap is null.

[img, map] = imread('1.jpg');

map = []

>> [indimg,map1] = rgb2ind(img,32);

>> imwrite(indimg,map1,'new.jpg');

>> [img, map] = imread('new.jpg');

>> map

map = []

Answer 1

Your are writing the image in JPEG format and imwrite converts indexed images to RGB before writing data to JPEG files, because the JPEG format does not support indexed images.

Use the code below

[img, ~] = imread('yourImage.jpg');
[ind1, map1] = rgb2ind(img, 32);
imwrite(ind1, map1, 'yourImageNew.png'); % Don't change the extension to .jpg or .jpeg
[img2, map2] = imread('yourImageNew.png');