How can I detect a color percentage in a picture?

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fatema ali
fatema ali on 20 Nov 2019
Commented: DGM on 17 May 2022
I have a picture with different colors, but I mainly need the precentage of three colors. how can I do that in matlab?
  2 Comments
Daniel M
Daniel M on 20 Nov 2019
Edited: Daniel M on 20 Nov 2019
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
fatema ali on 20 Nov 2019
Edited: fatema ali on 20 Nov 2019
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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Answers (1)

Kavya Vuriti
Kavya Vuriti on 17 Feb 2020
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)));
Hope this helps.
  2 Comments
Aishwarya Ashok kumar
Aishwarya Ashok kumar on 17 May 2022
As this code is showing us an error can u help us go solve this error
DGM
DGM on 17 May 2022
You need to define the variables. You need to specify an image and select threshold values that are appropriate for your own needs.

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