How to compare two colors?

Question

Samah EL QASSAH 2016-12-1

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/314938-how-to-compare-two-colors

评论： Samah EL QASSAH 2016-12-6

采纳的回答： Geoff Hayes

在 MATLAB Online 中打开

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?

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Answer 1

Geoff Hayes 2016-12-1

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https://ww2.mathworks.cn/matlabcentral/answers/314938-how-to-compare-two-colors#answer_245544

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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.