![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/197916/image.png)
Crop coloured padding of image
2 views (last 30 days)
Show older comments
So this is pretty much a follow-up question to this one I asked yesterday, but now I'm interested in cropping coloured padding (attachment for test-image-2.jpg). With the answer from Walter on the previous question, I tried to do it like this:
I = imread('test-image-2.jpg');
rI = I(:,:,1);
gI = I(:,:,2);
bI = I(:,:,3);
Rw = all(rI == 237); %red channel value
Gw = all(gI == 27); %green channel value
Bw = all(bI == 36); %blue channel value
%mask
Rmaskc = all(Rw, 1);Rmaskr = all(Rw, 2);
Gmaskc = all(Gw, 1);Gmaskr = all(Gw, 2);
Bmaskc = all(Bw, 1);Bmaskr = all(Bw, 2);
%set to 0
rJ = rI; rJ(Rmaskr,:,:) = 0; rJ(:,Rmaskc,:) = 0;
gJ = gI; gJ(Gmaskr,:,:) = 0; gJ(:,Gmaskc,:) = 0;
bJ = bI; bJ(Bmaskr,:,:) = 0; bJ(:,Bmaskc,:) = 0;
%RED
rJ( ~any(rJ,2), : ) = []; %rows
rJ( :, ~any(rJ,1) ) = []; %columns
%GREEN
gJ( ~any(gJ,2), : ) = []; %rows
gJ( :, ~any(gJ,1) ) = []; %columns
%BLUE
bJ( ~any(bJ,2), : ) = []; %rows
bJ( :, ~any(bJ,1) ) = []; %columns
IM = cat(3, rJ, gJ, bJ);
It crops the sides just fine (the small strokes on sides have different RGB values so guess thats ok), but the top/bottom is not getting cropped.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/197887/image.jpeg)
So I'm a bit confused on why the sides get cropped decently, but for some reason the top/bottom gets ignored
0 Comments
Accepted Answer
Image Analyst
on 14 Oct 2018
Try this:
rgbImage = imread('test-image-2.jpg');
rI = rgbImage(:,:,1);
gI = rgbImage(:,:,2);
bI = rgbImage(:,:,3);
subplot(2, 2, 1);
imshow(rgbImage);
title('Mask', 'FontSize', 16);
mask = ~((rI == 237) & (gI == 27) & (bI == 36));
subplot(2, 2, 2);
imshow(mask);
title('Mask', 'FontSize', 16);
[maskRows, maskColumns] = find(mask);
row1 = min(maskRows);
row2 = max(maskRows);
col1 = min(maskColumns);
col2 = max(maskColumns);
maskedRGBImage = rgbImage(row1:row2, col1:col2, :);
subplot(2, 2, 3);
imshow(maskedRGBImage);
title('Masked Image', 'FontSize', 16);
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/197916/image.png)
More Answers (0)
See Also
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!