How can I detect a color percentage in a picture?

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fatema ali 2019-11-20

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评论： DGM 2022-5-17

I have a picture with different colors, but I mainly need the precentage of three colors. how can I do that in matlab?

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Daniel M 2019-11-20

编辑：Daniel M 2019-11-20

What do you mean percentage of a color?

Say you have a picture composed of some red, blue, and yellow. Do you mean you want to get the percentage of the picture that is red (etc.)?

If this is true, then, follow up question: are you looking for exact, unique colors (as in, it would consider different shades of red to be different colors), or you want a broader sense (as in, rgb values of [1 0 0] and [0.9 0 0] would both be considered red)?

fatema ali 2019-11-20

编辑：fatema ali 2019-11-20

yes exactly, like the precentage of red in a certain picture.

I want a broader sense of colors, like all shades of red are considered as one thing and so on.

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Answer 1

Kavya Vuriti 2020-2-17

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Hi,

It would be better if you first determine the RGB triplet limits for a specific color and count the number of pixels lying in the above range. The sample code could look like this:

% Read image
I = imread('your_image'); 
% Define RGB limits
redLowerLimit = your_value; 
redUpperLimit = your_value; 
blueLowerLimit = your_value; 
blueUpperLimit = your_value; 
greenLowerLimit = your_value; 
greenUpperLimit = your_value; 
% Number of pixels of required colour
requiredColor  = ( I(:,:,1) >= redLowerLimit & I(:,:,1) <= redUpperLimit ) & ...
    ( I(:,:,2) >= greenLowerLimit & I(:,:,2) <= greenUpperLimit ) & ( I(:,:,3) >= blueLowerLimit & I(:,:,3) <= blueUpperLimit ); 
% Percentage of colour in the image
percentColor =  100*(sum(sum(requiredColor))/(size(I,1)*size(I,2))); 