illumination problem in face detection application

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.

Answer 1

[Image Analyst]

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);

[selim]

so is this command below ok to understand brightness?

    mean_of_rgbImage = mean2(rgb2gray(rgbImage))

[Image Analyst]

That could do the job for you.