Create mask over image

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fadams18 2020-2-15

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https://ww2.mathworks.cn/matlabcentral/answers/505589-create-mask-over-image

评论： Image Analyst 2020-2-16

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);

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采纳的回答

Subhadeep Koley 2020-2-15

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/505589-create-mask-over-image#answer_415663

编辑：Subhadeep Koley 2020-2-15

peppersMask.png

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');

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Subhadeep Koley 2020-2-15

@ 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.

fadams18 2020-2-15

Thank you!

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Image Analyst 2020-2-15

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/505589-create-mask-over-image#answer_415714

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));

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fadams18 2020-2-16

And how are we supposed to know what the mask should be? Thats what i said in the reply. The mask is an image of just text and when added to the image it gives the above image. I just want to know a good way to create this text mask.

Image Analyst 2020-2-16

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: