How to vectorize this function

Hi.

I have a series of images all with the same background but varying foregrounds. I'm looping through all these images and taking median pixel values to calculate the background so I can perform background subtraction. It works well but the code is slow because it contains a double for loop. How can I vectorize the following code?

    for x = 1:480
        for y = 1:640
            median_bg_RedValues(x,y) = median(bg_RedValues(x,y,1:actualNumOfImages));
            median_bg_GreenValues(x,y) = median(bg_GreenValues(x,y,1:actualNumOfImages));
            median_bg_BlueValues(x,y) = median(bg_BlueValues(x,y,1:actualNumOfImages));
        end
    end

median_bg_Red/Green/BlueValues is a 480*640 matrix, and bg_Red/Green/BlueValues is a 480x640x40 image, and I want to take the median of each cell's 40 elements (these 40 elements are the different pixel values for the 40 images).

How can I make this faster using vectorization?

Thanks.

Answer 1

[Andrei Bobrov]

median_bg_RedValues   = median(bg_RedValues,  3);
median_bg_GreenValues = median(bg_GreenValues,3);
median_bg_BlueValues  = median(bg_BlueValues, 3);

[Faizan Tahir]

This works, thanks a lot for the help.

[Andrei Bobrov]

Please accept this answer.

[Faizan Tahir]

Done, thanks again.

[Andrei Bobrov]

Thank you Faizan!