How can I use one plane of RGB as a mask for other planes and generate new image?
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Kamran Moradi
am 21 Aug. 2015
Kommentiert: Image Analyst
am 31 Jul. 2019
Original = imread('Image.tif');
[x,y,n]=size(Original);
% %-------------------------------Red Plane
Red(:,:,2)=zeros(x,y);
Red(:,:,3)=zeros(x,y);
Red(:,:,1)= Original(:,:,1);
%--------------------------------- Green Plane
Green(:,:,3)=zeros(x,y);
Green(:,:,1)=zeros(x,y);
Green(:,:,2)= Original(:,:,2);
% -- - - - - - - - - -------------- Blue Plane
Blue(:,:,2)=zeros(x,y);
Blue(:,:,1)=zeros(x,y);
Blue(:,:,3)= Original(:,:,3);
%-------------------------converts the green planes to Black and White to make mask
GreenBW= im2bw(Original(:,:,2));
OriginalMasked(:,:,1) = GreenBW.*Red(:,:,1);
OriginalMasked(:,:,2) = Green(:,:,2);
OriginalMasked(:,:,3) = GreenBW.*Blue(:,:,3);
imshow(OriginalMasked);
2 Kommentare
Akzeptierte Antwort
Walter Roberson
am 21 Aug. 2015
When you are creating Red, Green, Blue, copy over Original first so that you get the correct datatype for the destination. Currently you are copying it last.
4 Kommentare
Image Analyst
am 21 Aug. 2015
Be careful about using non-standard definitions for x and y like you did. That usually eventually leads to trouble. Most people would do
[y, x] = size(TwoDMatrix);
Of course you didn't do that, and you did something even more risky or dangerous - you used it on an image read in from imread(). Why is it dangerous to use
[x, y] = size(theImage);
instead of
[rows, columns, numberOfColorChannels] = size(theImage);
(besides just swapping x and y)? Well, read this: http://blogs.mathworks.com/steve/2011/03/22/too-much-information-about-the-size-function/
If you don't use a third argument on an image array, and the image array is a color image, the second argument ("x" or "y" as you called it) will actually be the number of columns multiplied by the number of color channels.
Weitere Antworten (2)
Image Analyst
am 21 Aug. 2015
An alternate way to mask an RGB image by a logical 2D mask image, promoted by Sean, is this:
% Mask the image using bsxfun() function
maskedRgbImage = bsxfun(@times, rgbImage, cast(mask, 'like', rgbImage));
1 Kommentar
Negesse Tadesse
am 31 Jul. 2019
does it help for image compresson?
1 Kommentar
Image Analyst
am 31 Jul. 2019
Does what help with image compression? Masking? It will make the images smaller because much of the image is replaced by a constant number.
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