gray2rgb conversion

Unable to perform assignment because the size of the left side is 245-by-744 and the size of the right side is 245-by-248-by-3.

Error in untitled>gray2rgb (line 20)

rgb(:,:,1)=Image;

Error in untitled (line 8)

rgb=gray2rgb(I);

[Shashank Sharma]

RGB Images are three channel. Each pixel has it's own R, G, B values.

A grayscale has only one channel.

The gray2rgb function returns a m by n by 3 matrix for an input of m by n image.

If you have predifined the size of rgb it will cause the above error.

Answer 1

[Walter Roberson]

When you allocated memory for the rgb array, you used something like,

[rows, cols] = size(Image);
rgb = zeros(rows, cols, 3);

This is not correct code when Image is RGB. When you have

[var1, var2, var3, ..., varn] = size(Array)

and Array has more than n dimensions, then the last entry (varn here) will be the product of all remaining dimensions.

[rows, cols] = size(Image);

is not the same as

image_size = size(Image);
rows = image_size(1); cols = image_size(2);

What you should use is

rgb = zeros(size(Image));