MATLAB: Illumination problem in face detection application

brightnessface detectionillumination

Hello everyone,
   I am dealing with face detection. I have a question.
   1) I can change the brightness of an image adding a number. (I=I+50;)
   How can I learn or calculate the level of illumination,brightness so that I can add or subtract some values and the image can get suitable for my parameters?
   Am I supposed to calculate mean of absolute? What do you suggest?
                                                          Thanks in advance.

Best Answer

You can get the "brightness" of each color channel by (optionally) extracting the color channels:
% Extract the individual red, green, and blue color channels.
redChannel = rgbImage(:, :, 1);
greenChannel = rgbImage(:, :, 2);
blueChannel = rgbImage(:, :, 3);
To get the brightness for a particular pixel, for example at row 2, column 42, you can just reference it:
redValue = redChannel(2, 42);
greenValue = greenChannel (2, 42);
blueValue = blueChannel (2, 42);
Or just use the original rgb image:
redValue = rgbImage(2, 42, 1);
greenValue = rgbImage(2, 42, 2);
blueValue = rgbImage(2, 42, 3);
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