How to get coloured layer from an rgb image in matlab.

Hi. I want to extract all three layers from rgb colour image.For red layer i want it is red colour and similarly for green layer i need the image in green shade. simple code is attached but it increase the size of the image which i dont want. If an input image is of small size I need the output of the same size.

I1=imread('Hello.png')
I1 = I1(:,:,2);
 R=image(I1), colormap([zeros(256,1),[0:1/255:1]', zeros(256,1)]);
 figure;
 imshow(R,[])

Answer 1

[Walter Roberson]

I1 = imread('Hello.png');
R = 0 * I1; R(:,:,1) = I1(:,:,1);
G = 0 * I1; G(:,:,2) = I1(:,:,2);
B = 0 * I1; B(:,:,3) = I1(:,:,3);
subplot(1,3,1)
image(R)
subplot(1,3,2)
image(G)
subplot(1,3,3)
image(B)

[sadiqa ilyas]

it works Thanks a lot

[sadiqa ilyas]

I have tried and it works for all three layers but when I applied the same command on the encrypted image It does not produce the desire result

image(I1), colormap([zeros(256,1),[0:1/255:1]', zeros(256,1)]);
%   figure;
%  imshow(I1,[])
:
:
:
EncImg=uint8(EncImg);
image(EncImg),colormap[zeros(256,1),[0:1/255:1]',zeros(256,1)])

[Walter Roberson]

Notice that my code has no colormap. colormap is ignored for rgb images.

In a previous Question you were incorrectly losing the third dimension of your rgb image, and it is not clear that you fixed that problem. When you are processing an rgb image and need to later restore the processed image to the original, then the processed version should usually be rgb as well.

[sadiqa ilyas]

well your first answer works well for different layers but not giving desired result for encrypted image

[Walter Roberson]

If EncImg has 3 dimensions then my suggestion should work. If EncImg only has two dimensions then you probably have a problem with your code since you were recently working on processing color images.

[sadiqa ilyas]

EncImg is only an enciphered image of green layer, so it is 1 dim

[Walter Roberson]

Then reshape it to 2d and store it as (:, :, 2) of a 3d matrix of zeros like I showed.