MATLAB Answers

1

how to arrange RGB image in a plane

Asked by Bibin George on 13 Aug 2018
Latest activity Commented on by Image Analyst
on 1 Sep 2018

I need to create an input plane by separating an rgb image into individual images red, green and blue channels and placing them in specific points of the 2d plane. I tried it using uint8 array but did not yield the desired result. Could someone help me with this problem please.

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3 Answers

Answer by Walter Roberson
on 13 Aug 2018

R = 0 * YourRGBImage;
G = R;
B = R;
R(:,:,1) = YourRGBImage(:,:,1);
G(:,:,2) = YourRGBImage(:,:,2);
B(:,:,3) = YourRGBImage(:,:,3);
image([xmin_1, xmax_1], [ymin_1, ymax_1], R);
hold on
image([xmin_2, xmax_2], [ymin_2, ymax_2], R);
image([xmin_3, xmax_3], [ymin_3, ymax_3], R);
hold off

The xmin_1 and so on reflect the "specific points on the 2d plane" that the centers of the lower left and upper right pixels are to be placed at.

  6 Comments

What I really want is arrange the red, green and blue channels of two input images in such a way. I have some calculations that involving the entire plane later on in the rest of the program.

I am using matlab 2014b

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Answer by Image Analyst
on 21 Aug 2018

In case you want a copy and paste operation where you can paste some rectangular image at a specified location on a2-D canvass, see attached demo.

  5 Comments

Please note that i am arranging two images

Input = uint8(zeros(height_input, width_input, 3));
%3. Arrange the red, green and blue portion of the input image separately
% on the left hand side of the input plane.
Input(1:height_t, 1:width_t, 1) = t(:,:,1);
Input(height_t*2+1:height_t*3, 1:width_t, 2) = t(:,:,2);
Input(height_t*4+1:height_t*5, 1:width_t, 3) = t(:,:,3);

and a similar change for the other image.

It is working as i expected now. Thanks a lot

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Answer by Image Analyst
on 21 Aug 2018

In case you want to take color channels and put them at different locations vertically, see attached demo.

rgbImage = imread('peppers.png');
% Extract the individual red, green, and blue color channels.
redChannel = im2double(rgbImage(:, :, 1));
greenChannel = im2double(rgbImage(:, :, 2));
blueChannel = im2double(rgbImage(:, :, 3));
H(1) = slice(repmat(redChannel,[1 1 2]),[],[], 1); %slice() requires at least 2x2x2
set(H(1),'EdgeColor','none') %required so image isn't just an edge
hold on
H(2) = slice(repmat(greenChannel,[1 1 2]),[],[], 2); %slice() requires at least 2x2x2
set(H(2),'EdgeColor','none') %required so image isn't just an edge
H(3) = slice(repmat(blueChannel,[1 1 3]),[],[], 3); %slice() requires at least 2x2x2
set(H(3),'EdgeColor','none') %required so image isn't just an edge
hold off
colormap(gray(256))
axis ij

  3 Comments

I have the same question but I need this image in a horizontal plane with red, green and blue colour.

It appears to me that Image Analyst's code puts them vertically, so it is not clear what you would like done differently ?

hardik, now you say horizontally but we still do not know exactly how you'd like it to look. Why don't you just use subplot() or montage(). If not, then create a picture of what you want and upload it.

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