1 | initial version |
If the background is completely black you can simply use cvtColor(src,dst,CV_RGB2GRAY) to transfer this image into gray image. Than use findContours on dst, and check number of polygons.
If the background is not black, but at least uniform and you know its color, you can use compare(src,color,dst,CMP_EQ) to determine which pixels are part of the background and which are not. Again use findContours on dst.
If the background is not uniform, the problem became more complicate and will require more complicate solutions. Also note that detection of hue is not something that will help you for blob detection (usually).