The OpenGLES 2.0 render manager now supports compressed textures on supported hardware. The formats supported are PVRTC1, both 4BPP and 2BPP. This compression format is supported on most PowerVR graphics chipsets.
To determine if the chipset supports it, running Storyboard with a verbosity level of 6 (-vvvvvv_ will print out, on startup, the GLES extensions supported by the chip. If PVRTC is supported, you will see GL_IMG_texture_compression_pvrtc in the extension string list.
Storyboard will manually decode these images if the runtime being used does not support them. Should a project that was running on a PowerVR chip and using compressed images be run on a SW runtime that does not support them, the images would still decode and render correctly, just without HW acceleration.
PVRTC provides a 8x improvement in memory size (A 1024x1024x4 BMP would take 4MB of memory, whereas a PVRTC image would take 512K)
Compression tools can be found at: