I already have a preview working from the gray scale camera. I capture each frame as 8-bit generic data and use IPU unit to convert 8-bit gray scale raw data into ARGB8888. To do that I use custom color space conversion matrix and YUV->RGB conversion IPU task. All capture buffers including one from the output of the IPU are allocated from the native window. At this point, I submit output from IPU to the preview window. I'd like to insert some additional GPU processing (custom shading) in between i.e. after IPU and before submitting to preview window. My system is imx6 android ics 13.4.1.04. Can you please give me some ideas how this could be done? If I could look into some code examples that would be great.