如果我在内核函数中调用OpenCV GPU模块中的函数，它会起作用并且会更快吗？

Question

OpenCV has a gpu. GPU-accelerated Computer Vision gpu. GPU-accelerated Computer Vision module ( http://docs.opencv.org/modules/gpu/doc/gpu.html ). There are many functions which is already use GPU techniques. So I can directly use the function OpenCV applies. But I wonder whether it would be faster if I write my own kernel and in each kernel I call function of OpenCV GPU module. This is in the case I have many images. To handle each image I call OpenCV funtion in GPU module. Then it would be parallel-nested-parallel.

Answer 1

Your question is not entirely clear to me, but I would like to say this: it's impossible to say which would be faster, unless somebody already implemented that same algorithm using the approach you have in mind, and then shared a report about the benchmark tests.

There's a number of factors involved:

• It depends on the type of operation you are trying to implement : techniques that have a high arithmetic intensity are better fit for GPUs for sure, however, not all problems can be modeled for GPUs.
• The size of the input images matter : wasting time sending data from RAM to the GPU might not compensate in the end, so running the algorithm on the CPU can be faster for small images.
• The model/power of the CPU/GPU : if the computer has a really crappy GPU, then it's probably better to run the algorithms on the CPU.

What I'm saying is: don't assume OpenCV GPU's module will always run it's algorithms faster than the CPU you got. Test it, measure it! The only way to know for sure is through experimentation and benchmark.