How to compare color images

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syafini alias
syafini alias 2017-12-10
编辑： Image Analyst 2017-12-15
I have used the coding below but it cannot read my rgb values. can someone helps me.
% Read in the Base Image
imgblue = imread('Blue.jpg');
blue = imcrop(imgblue,[60 72 580 300]);
figure, imshow(blue), title('Blue Image'), impixelinfo;
Rb = blue(:,:,1);
Gb = blue(:,:,2);
Bb = blue(:,:,3);
imggreen = imread('Green.jpg');
green = imcrop(imggreen,[60 72 580 300]);
figure, imshow(green), title('Green Image'), impixelinfo;
Rg = green(:,:,1);
Gg = green(:,:,2);
Bg = green(:,:,3);
imgyellow = imread('Yellow.jpg');
yellow = imcrop(imgyellow,[60 72 580 300]);
figure, imshow(yellow), title('Yellow Image'), impixelinfo;
Ry = yellow(:,:,1);
Gy = yellow(:,:,2);
By = yellow(:,:,3);
%figure, imshow(Ryellow), impixelinfo;
% Read in the Input Image
imgtest = imread('Test.jpg');
test = imcrop(imgtest,[60 72 580 300]);
figure, imshow(test), title('Test Image'), impixelinfo;
Rt = test(:,:,1);
Gt = test(:,:,2);
Bt = test(:,:,3);
if (Rt==Rb)&&(Gt==Gb)&&(Bt==Bb)
h = msgbox('The colour image is BLUE','Blue');
else if (Rt==Rg)&&(Gt==Gg)&&(Bt==Bg)
h = msgbox('The colour image is GREEN','Green');
else if (Rt==Ry)&&(Gt==Gy)&&(Bt==By)
h = msgbox('The colour image is YELLOW','Yellow');
else
h = msgbox('Operation Completed','Unknown');
end
end
end
  4 个评论
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Image Analyst
Image Analyst 2017-12-14
Exactly what does "cannot read my rgb values" mean? Does imread() work or does it throw an error?
syafini alias
syafini alias 2017-12-14
when i run this coding this error displays in command window
Undefined operator '==' for input arguments of type 'cell'.
Error in test1 (line 45) if (Rt==Rb)&&(Gt==Gb)&&(Bt==Bb)

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回答（2 个）

YT
YT 2017-12-14
编辑：YT 2017-12-14
While running your code, I got
Operands to the || and && operators must be convertible to logical scalar values
Replace '&&' by '&' in all these (else)if-statements worked for me using your example
& = array
&& = scalar
  1 个评论
syafini alias
syafini alias 2017-12-15
i try to convert from && to & as you mentioned before but this error displays in command window
Undefined operator '==' for input arguments of type 'cell'.
Error in test1 (line 45) if (Rt==Rb)&(Gt==Gb)&(Bt==Bb)

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Image Analyst
Image Analyst 2017-12-14
Use isequal():
if isequal(Rt, Rb) && isequal(Gt, Gb) && isequal(Bt, Bb)
h = msgbox('The colour image is BLUE', 'Blue');
elseif isequal(Rt, Rg) && isequal(Gt, Gg) && isequal(Bt, Bg)
h = msgbox('The colour image is GREEN', 'Green');
elseif isequal(Rt, Ry) && isequal(Gt, Gy) && isequal(Bt, By)
h = msgbox('The colour image is YELLOW', 'Yellow');
else
h = msgbox('The colour is unknown','Unknown');
end
  2 个评论
syafini alias
syafini alias 2017-12-15
i try to use the coding as you give but the msgbox only shows unknown even i insert value for RGB same as the yellow color. it suppose to be show yellow.
Image Analyst
Image Analyst 2017-12-15
编辑：Image Analyst 2017-12-15
They're not exactly equal. The test image was red and the reference colors were cyan, yellow, and green.

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