How to compare color images

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

[Image Analyst]

You forgot to attach any of your images. So I'll wait until tomorrow until I run/test your code. Because

imgblue = imread('Blue.jpg');

should read your values. If it can't, then your image is corrupted, but I can't tell because you didn't attach it.

Also, read this link and fix your code formatting.

Plus, you should not do this

if (Rt==Rb)&&(Gt==Gb)&&(Bt==Bb)

since those are images and each == will produce a binary image, and it doesn't make sense to do && with a binary image!

[syafini alias]

what command should i use then?

[Image Analyst]

Exactly what does "cannot read my rgb values" mean? Does imread() work or does it throw an error?

[syafini alias]

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)

Answer 1

[YT]

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

[syafini alias]

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)

Answer 2

[Image Analyst]

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

[syafini alias]

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]

They're not exactly equal. The test image was red and the reference colors were cyan, yellow, and green.