Need help with creating or modifying an RGB image.

% read in a jpg image

%

z=imread('Paraglider.jpg');

size(z)

%

% separate out the red, blue, and green components

%

r=z(:,:,1); % r=z(rows, columns, first page)

b=z(:,:,2);

g=z(:,:,3);

%

% look at the components

%

figure(6),clf

subplot(2,2,1),imshow(z),title('composite')

subplot(2,2,2),imshow(r),title('red')

%

% recombine components

%

figure(7),clf

subplot(2,2,1),imshow(cat(3,r,b,g)),title('r,b,g')

%

% write an image to a jpg file

%

outimage=cat(3,g,r,b);

imwrite(outimage,'ParaGRB.jpg')

[KALYAN ACHARJYA]

Issue?

Answer 1

[KALYAN ACHARJYA]

I'm not sure how to separate out the red, blue, and green components of an image like the Paraglider.jpg that I'm using .

As you already showing the same in the code

%Read the image
image1=imread('image file name.format');
r=image1(:,:,1);     % This line gives you red component of the image
b=image1(:,:,2);     % This line gives you blue component of the image
g=image1(:,:,3);     % This line gives you green component of the image

Please response in the comment section only.

[JC]

But these codes don't give me separate images as subplots in red, blue, and green of the Paraglider.jpg. They all show up as 4 gray images when I use the following codes below.

% look at the components

%

figure(6),clf

subplot(4,2,1),imshow(z),title('composite')

subplot(4,2,2),imshow(r),title('red')

subplot(4,2,3),imshow(b),title('blue')

subplot(4,2,4),imshow(g),title('green')

[KALYAN ACHARJYA]

Are you loking for this one? Change according for composite cat(..)

im=imread('test.jpg');
%..........^^^^^^^...Change the image file name
subplot(221);imshow(im), title('RGB Image');
%% Red Component
red_com=im;
red_com(:,:,2:3)=0;
subplot(222); imshow(red_com); title('Red');
%% Green Componnet
green_com=im;
green_com(:,:,1)=0;
green_com(:,:,3)=0;
subplot(223);imshow(green_com); title('Green');
%% Blue Component
blue_com=im;
blue_com(:,:,1:2)=0;
subplot(224);imshow(blue_com); title('Blue');

[JC]

Right that's what I wanted to do for my image. Thank you.

[JC]

Would you also happened to know how to recombine the component and then write an image to a JPEG file?

% recombine components
%
   figure(7),clf
   subplot(2,2,1),imshow(cat(3,r,b,g)),title('r,b,g')
%
% write an image to a jpg file
%
   outimage=cat(3,g,r,b);
   imwrite(outimage,'ParaGRB.jpg')

[KALYAN ACHARJYA]

Those all red_com, blue_com and green_com are RGB images shown in respective components.

Red color shows means in RGB, in the following you extract the r,g, b components (Gray Representation)

im=imread('test.jpg');
%subplot(221);imshow(im), title('RGB Image');
%% Gray-Red Component
red_com=im(:,:,1);
subplot(221); imshow(red_com); title('Red Component');
%% Gray-Green Componnet
green_com=im(:,:,2);
subplot(222);imshow(green_com); title('Green Component');
%% Blue Component
blue_com=im(:,:,3);
subplot(223);imshow(blue_com); title('Blue Component');
%% Blue Component
combine=cat(3,red_com,green_com,blue_com);
subplot(224);image(uint8(combine)); title('Composite');