Correct way to use accumulator (SOLVED) [closed]

edit

I have been trying to create a foreground subtractor which accumulates a number of frames upon program starts and uses the generated image to detect foreground objects which may enter the view in a later time. However I am confused which image type I should use here in order to avoid "Assertion failed (func != 0) in accumulate" in one hand and end results with wrong colors on the other hand.

Code:

void Test::initBackgroundImage() {
    int totalCount = 3;
    int currentCount = 0;

    Mat camFrame;
    while(currentCount < totalCount) {
        cam >> camFrame;

        if(bgImg.empty()) {
            cam >> bgImg;
            bgImg.create(camFrame.size(), CV_32FC3);
        }

        accumulate(camFrame, bgImg);

        currentCount++;
    }
}

NOTE: Variables are all initialized in the constrcuctor.

Why does my code generate an image with wrong colors?

UPDATE:

I found out on this blog that adding the following line:

convertScaleAbs(bgImg, bgImg);

after the loop corrects the colors. Can someone please explain what exactly happens here?

UPDATE 2:

I just found out that the produced image has been correct. But since it was a 32 bit integer image, it was shown with different colors when calling imshow. See docs for more.