How do you use OpenGLES to open an image file, do some work, then save the image file, in the background (offline)?

Question

So I'd like to create a class that accepts a CGImage from an image file I just read from disk, does work on that image texture (color transformations) then returns the texture as a CGImage and does all this in the background w/out drawing to screen. I've looked at Apple's demo app on GLImageProcessing but it draws all the processing to the screen and I've seen bits and bites of how to do parts of what I want but can't assemble it.

Any suggestions would be greatly appreciated.

Thanks

Answer 1

You will have to use Framebuffer Objects (FBOs) to draw offscreen, but you still need a GL rendering context.