How to compare color images

Question

syafini alias 2017-12-10

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/372128-how-to-compare-color-images

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

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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 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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Answer 1

YT 2017-12-14

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/372128-how-to-compare-color-images#answer_296303

编辑：YT 2017-12-14

在 MATLAB Online 中打开

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

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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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Answer 2

Image Analyst 2017-12-14

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/372128-how-to-compare-color-images#answer_296305

在 MATLAB Online 中打开

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

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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.