I'm using version 3.1 and need to perform an RGB operation on an image and output a greyscale image. I know OpenCV uses kernels for things but since BaseFilter was privatized in 3.1 (why?..) it is no longer a trivial thing to do.
How would one do this with OpenCV? I've seen several threads saying you can't, but I sincerely hope that's not the case as that really limits the usefulness of this library for us.