OpenCV GPU ( CUDA ) Template matching and FFT implementation

Question

I am using opencv GPU::matchTemplate() on GTX690.

I checked the function internally and found that gpu::matchTemplate() is not using any FFT in the process, while its CPU counterpart does.

My question is, what is the reason behind not using FFT in the GPU?

Answer 1

OpenCV GPU match template implementation uses FFT if template size if bigger than some threshold (https://github.com/Itseez/opencv/blob/2.4/modules/gpu/src/match_template.cpp#L147), otherwise it uses brute-force approach,