Efficient Frame Buffer Downsampling with PowerVR

PowerVR hardware provides an efficient fast path for downsampling frame buffer attachments, which can be extremely useful for certain post-processing techniques such as bloom and screen space reflections. The OpenGL ES function glFramebufferTexture2DDownsampleIMG allows an application to attach a buffer to a frame buffer which is at a lower resolution than the frame buffer itself, and have the hardware automatically downsample the attachment.

All PowerVR hardware exposes at least a 2x2 downscale. Other downsampling modes may be available depending on the exact hardware, and it is possible for an application to query this information at runtime.

For more information on this extension, please refer to the IMG_framebuffer_downsample Khronos page.