I want RGB to HSV conversion. What changes are required in the following code?

X = im2double(imread('path'));

R = X(:,:,1);

G= X(:,:,2);

B = X(:,:,3);

z = zeros(size(R));

Rimg = cat(3, R, z, z);

Gimg = cat(3, z, G, z);

Bimg = cat(3, z, z, B);

L256 = linspace(0,1,256).';

z256 = zeros(256,1)

mapR= [L256, z256, z256];

mapG= [z256, L256, z256];

mapB = [z256, z256, L256];

figure; image(Rimg); colormap(mapR); colorbar();

figure; image(Gimg); colormap(mapG); colorbar();

figure; image(Bimg); colormap(mapB); colorbar();

[Adam]

Well, converting to HSV would be useful. I don't really understand what the aim of any of your lines of code are if your aim is simply to convert from rgb to hsv. Either use

doc rgb2hsv

to do it in one function or if you have to write your own you can easily search online for the algorithm that is needed.

[Walter Roberson]

Applying a colormap to an RGB image has no practical use. Your Rimg and so on are RGB images that just happen to have a bunch of zeros.

colormap() is for indexed and grayscale images only.

[Guillaume]

Indeed it is very unclear what the code given has got to do with conversion to HSV which is trivially achieved with rgb2hsv.

The whole code is simply a very complicated way of achieving the same as:

X = im2double(imread('path'));
figure; imshow(X .* cat(3, 1, 0, 0));
figure; imshow(X .* cat(3, 0, 1, 0));
figure; imshow(X .* cat(3, 0, 0, 1));

[Walter Roberson]

X .* cat(3, 1, 0, 0) requires R2016b or later.

Answer 1

[Image Analyst]

Your code doesn't do anything useful at all. Abandon it all, except the imread() and try this:

hsvImage = rgb2hsv(X);