Conversion of grayscale image into RGB and CIELAB color space

HI everyone,

please guide me if anyone know. I have Grayscale images (0-255) and i want to convert that grayscale images into RGB images (3 channels) and CILab color space images. please help me in coding.

ref grayscale image is attach.

Answer 1

[Rik]

To convert a grayscale image to RGB you need a colormap.

G=imread('https://www.mathworks.com/matlabcentral/answers/uploaded_files/795434/vidf6_33_002_f010.png');

map=colormap; %select the active colormap, probably not what you want

%convert to RGB
RGB=ind2rgb(G,map);imshow(RGB)

As for the conversion to CIELab, you should read this answer by Image Analyst.

Answer 2

[DGM]

I would think that the obvious choice would be

% an I/RGB image
inpict = imread('https://www.mathworks.com/matlabcentral/answers/uploaded_files/795434/vidf6_33_002_f010.png');

% expand it to RGB
if size(inpict,3) == 1
    rgbpict = repmat(inpict,[1 1 3]);
else
    rgbpict = inpict;
end

% convert to LAB
labpict = rgb2lab(rgbpict);

... of course if your images are all grayscale, what's the advantage of converting them to LAB? Unless you're trying to feed grayscale images into a process that handles things in LAB, you're generating a bunch of useless extra data. There is no information in the chroma channels, so the only thing of value is L*. If all you need is L*, you can just do.

% convert to L*
lpict = rgb2lightness(rgbpict);