C++ Library to combine Images (im1+im2+...)

Requirements: -Cross platform . -Basically If you have N streams, during a processing round you will operate with Nx2 inputs. - YUV420 data support is preferred if possible. but RGB24 is ok too. Fastest Algo is best. For example if we have 2 streams: -Image1(rgb bytes) from stream1 -Image2(rgb bytes) from stream2 Image1+Image2 will be placed side by side to create ImageTmp(rgb). ImageFinal(rgb). So You will have to provide at least two functions similar to these: FUNCTION: combineImages( ) INPUT: std::list of N images RGB-buffers OUTPUT: RGB buffer