Create mask over image
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fadams18
on 15 Feb 2020
Commented: Image Analyst
on 16 Feb 2020
I am trying to create mask over an image (input). I already used photoshop to create a mask (which is basiclly an image with same size as input image) t which I add to the original image. Then I use NMF to reconstruct the original image. but it doesnt seem to be working. Am I doing the masking correctly? Any other ideas?
Input=im2double(imread('dataset/3.jpg')); % RGB original image
mask = double( mat2gray( im2double(imread('dataset/mask1.png')) ) == 1 ); % loading a grayscale image icreated in photoshop
if size(mask,3)==1 && size(input,3)>1
mask = repmat(mask,[1,1,size(input,3)]);
end
CorruptedImage = mask.*Input
Q=mask(:,:,1);
Red=CorruptedImage(:,:,1);
Gre=CorruptedImage(:,:,2);
Blu=CorruptedImage(:,:,3);
0 Comments
Accepted Answer
Subhadeep Koley
on 15 Feb 2020
Edited: Subhadeep Koley
on 15 Feb 2020
You should not use the variable name input as it shadows a MATLAB built-in function. Use the example code below.
close all; clc;
img = im2double(imread('peppers.png'));
figure; imshow(img);
title('Original RGB image');
mask = im2double(imread('peppersMask.png')); % Download the mask attached below
figure; imshow(mask);
title('Mask');
if size(mask, 3) == 1 && size(img, 3) > 1
mask = repmat(mask, [1, 1, size(img, 3)]);
end
CorruptedImage = mask .* img;
Q = mask(:, :, 1);
Red = CorruptedImage(:, :, 1);
Gre = CorruptedImage(:, :, 2);
Blu = CorruptedImage(:, :, 3);
figure; imshow(CorruptedImage);
title('CorruptedImage');
figure; montage(CorruptedImage, 'Size', [1, 3]);
title('R, G, B component of the CorruptedImage');
3 Comments
Subhadeep Koley
on 15 Feb 2020
@ fadams18
1. You can not use the pepperMask image for your image. I created that mask only for giving an example. Also you said that " I already used photoshop to create a mask...". Therefore you can use the mask, which you have created.
2. Yes, it is working as of version R2019b.
3. Actually "==1" is not required. I have upated my answer.
More Answers (1)
Image Analyst
on 15 Feb 2020
To mask an image with a binary image, which will blacken the image outside where the mask is true:
% Method to multiplication channel by channel.
% Mask the image using bsxfun() function to multiply the mask by each color channel or slice individually.
maskedRgbImage = bsxfun(@times, rgbImage, cast(mask, 'like', rgbImage));
8 Comments
Image Analyst
on 16 Feb 2020
You said that the authors already had the mask and that they added it to the original image on the left. So why don't you just type up something in a word processor program then type alt-PrintScreen (in Windows) or use the snipping tool to capture a screenshot into a file?
Or Google "text image" and download one:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/271975/image.png)
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