Efficient Background subtraction with OpenCV

background-subtraction, opencv

Solution

Okay, I don't understand how TempFrame (your foreground) could be greyscale if you are using background subtraction. You must be using a very special algorithm. But assuming TempFrame is greyscale, then you would do this:

cv::Mat mask = tempFrame > 0.5;

cv::Mat outFrame;
capturedFrame.copyTo(outFrame, mask);

That is OpenCV 2.0 code above. The number 0.5 is a threshold, you'll need to set it to something appropriate. If you're not using floating-point images, you'd probably set it to 128 or something like that. This is the same thing in OpenCV 1.1 code:

CvMat* mask = cvCreateMat(tempFrame.rows, tempFrame.cols, CV_8UC1);
cvCmpS(tempFrame, 0.5, mask);

CvMat* outFrame = cvCreateMat(capturedFrame.rows, capturedFrames.cols, CV_32FC3);
cvCopy(capturedFrame, outFrame, mask);

Problem

I want to do background subtraction in a video file using OpenCV method. Right now I'm able to do background subtraction, but the problem is that I couldn't get the output in color mode. All the output after subtracting the background is coming in grayscale color mode :(. I want to get the color information to the foreground which is the resulting output after background got subtracted. Can I do it using masking technique?? like the following procedure which I'm thinking about. - Capture Input -- `InputFrame` (RGB) - Process `InputFrame` - Subtract background, store foreground in `TempFrame` (which is coming in grayscale :( ) - Create a mask using `TempFrame` - Apply the created mask to the `InputFrame` - Get colored foreground as `OutFrame` I'm struck up with doing the masking using OpenCV. I'm just a very beginner in OpenCV. Please help me to overcome this. Thanks in advance.

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