Comment 7 for bug 673995

Like you, I don't know yet how matchTemplate operates on transparent pixels. I still have to dive deeper into the code. But it's possible that it ignores the alpha layer entirely. It would explain that transparent white could be a good fit for light background. If you try with transparent black, it will probably be better on dark backgrounds.

Anyway, I'll still investigate the OpenCV code, which is interesting in its own right.

Thanks.