How to compare two colors?

Hi!

I want to compare the color of a button with another color. I wrote the code below:

     c = get(handles.showColor, 'BackgroundColor');
     color = 'green';
     st = strcmp(c,color);
     if(st == 1)
        axes(handles.axes1);
        img = imread('image\electronique.png');
        image(img);
        axis off;
      end;

is it correct? Can i compare c and color?

Answer 1

[Geoff Hayes]

Samah - with R2014a, if I create a pushbutton and then call

 get(handles.pushbutton1,'BackgroundColor')

an array of three elements is returned as

 ans =
    0.9255    0.9255    0.9255

The elements of this array correspond to the red, green, and blue components of the colour with values between zero and one. Your code

st = strcmp(c,color);

is attempting to compare a string with an array of numbers and so will fail. You would need to determine what the equivalent RGB colour for green would be. For example,

 greenClr = [0 1 0];

and then you would need to compare each element of greenClr with each element of c. However since these elements are doubles (not integers) you would need to compare the pairs within some tolerance. For example,

 myColour = rand(1,3);
 greenColour = [0 1 0];

 % compare the two
 if all(abs(myColour - greenColour) < 0.000001)
     fprintf('Colours are (near) identical!\n');
 else
     fprintf('Colours are not identical!\n');
 end

Note that since

 abs(myColour - greenColour) < 0.000001

returns a logical array of three elements, then we need to use all which returns true (1) or false (0) if all elements of the input array are one or not.

[Samah EL QASSAH]

Thank you so much! It's so helpful :)