I'm working on a Python (2.7.13) program that reads images from the webcam (refreshed on a separate thread), does a perspective transform, and puts the live video in a window on the screen, using opencv (3.2.0-dev). I get very low FPS (13) updating a 720x1280 output image with cv2.imshow(). If I remove the call to cv2.imshow() and keep the rest of the loop the same, it goes up to 75 FPS. What should I use in place of cv2.imshow() to get a reduce this image refresh bottleneck? I'm using a 2016 MacBook Pro with dedicated graphics card.
Do I need PyOpenGL for this, and if so are there any clear examples documented? I tried Pygame's blit function and did not see an improvement in FPS. I considered Pyglet which uses OpenGL, but I was not familiar with the paradigm of events used by Pyglet, and wasn't ready to rewrite my code if it turns out there's a more appropriate way to do it, as Pyglet seems to be mainly for games and some sources say it's not well maintained.
The imshow() feature is not really intended for real-time or streaming video display. You can easily run at frame rate using OpenGL, but there's quite a bit of effort involved. Have a look at PySDL which gives you a higher level API to OpenGL but is still designed for frame rate performance.