Convert an RGB image to grayscale but keep one color?
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A = imread('C:\FFOutput\gdgf\B.jpg'); B = rgb2gray(A); figure(1),imshow(B);
I have converted the image to a grayscale but don't know how to keep one color especially green.
回答（4 个）
yonatan gerufi
2014-9-7
编辑：yonatan gerufi
2014-9-7
Hi, there are several ways to do it,
i find it easy to do:
red_color = A(:,:,1);
green_color = A(:,:,2);
blue_color = A(:,:,3);
John
2014-9-7
I am guessing you want the green channel stored in a separate matrix. In your code, A is only read. Its value does not change after the call to rgb2gray. To get the green channel from A:
greenChannel = A(:,:,2);
Image Analyst
2014-9-7
0 个投票
I just answered this an hour ago for someone. See my comment http://www.mathworks.com/matlabcentral/answers/153732-question-concerning-color-segmentation-performance#comment_235875
3 个评论
Image Analyst
2014-9-7
Code is attached.
Jaja
2014-9-25
Image Analyst
2014-9-25
Why? That's pretty much what the original image is already.
Refer to this answer for more details on how this can be done. While that link includes multiple methods, I'm going to use MIMT replacepixels() for ease of use.
% this is a color image
rgbpict = imread('coloredChips.png');
% create a grayscale copy by some means
graypict = rgb2gray(rgbpict); % BT601 luma
% HSV ranges for masking
rangeR = [0.963 0.016; 0.258 1; 0.338 1];
rangeG = [0.380 0.453; 0.258 1; 0.338 1];
% create masks to select objects of specified colors
hsvpict = rgb2hsv(rgbpict);
maskR = all(hsvpict >= permute(rangeR(:,1),[2 3 1]),3) ...
| all(hsvpict <= permute(rangeR(:,2),[2 3 1]),3);
maskG = all(hsvpict >= permute(rangeG(:,1),[2 3 1]),3) ...
& all(hsvpict <= permute(rangeG(:,2),[2 3 1]),3);
% clean the masks
maskR = bwareaopen(maskR,100);
maskG = bwareaopen(maskG,100);
% composite the color and gray images using the masks
% replacepixels is from MIMT
outpictR = replacepixels(rgbpict,graypict,maskR);
outpictG = replacepixels(rgbpict,graypict,maskG);
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