OpenGL ES - Reducing texture quality and texture size

Is it possible to "degrade" the quality of textures in OpenGL ES? By degrade I mean make the images more pixelated/blocky/blurry etc.

My goal is to reduce the size of textures to help glReadPixels run faster (transfer开发者_开发百科 less bytes from VRAM to RAM).

Perhaps I can do something before calling glCopyTexImage2D such that the copied texture is lower quality (and hopefully a smaller size)?

Render your scene to an FBO (frame buffer object) that is a smaller size than the display.

Note that reducing the size of the textures used to render your scene won't reduce the size of the data glReadPixels has to read back.