Question

I just start to try MATLAB Project. I used to separate the Red, Green and Blue colors.
This is my function:

function x = colorsep(b) %
n = 256; % color is from 0->255, so it has 256
a = imread('peppers.png');


b=im2uint8(a);
x=figure; % create picture to put the image


subplot(2,2,1); %(2 rows, 2column, cell ti 1)
imshow(b),title('Full Color');


colorlist = {'Red','Green','Blue'};


gr = 0:1/(n-1):1;


for k=1:3

    cMap = zeros(n,3);
    cMap(:,k) = gr;
    subplot(2,2,k+1);
    imshow(ind2rgb(b(:,:,k),cMap)); %ind2r = index to rgb
    title(colorlist{k});
end
end    

Now I want to separate three color ( Pink, Yellow, Orange), what will I do? Anyone know about this? Thanks so much.

Answer 1

The question is incorrect. An image in the computer consists of 3 color channels

• Red
• Green
• Blue

What you are doing here is showing a single channel, with a colormap that corresponds to it.
By the way, the colormap is unnessecary, and you can show it like that (More natural)

function colorsep() %
    a = imread('peppers.png');
    colorlist = {'R','G','B'};    
    subplot(2,2,1);
    imshow(a);
    for k=1:3
        subplot(2,2,k+1);
        imshow( a(:,:,k));
        title(colorlist{k});
    end
end

If you want to separate it in another color space, you should first transform it to another color space – like LAB, and then show the channels separately.

If you want to find all “pink”,”yellow” objects, you should do a segmentation, and check objects mean color.

Please clarify what exactly you want.