What is the fastest way to load compressed images on iOS?

Question

I am writing an iOS app which need to load a lot of full-screen size images into OpenGL. Image storage space is a concern, so I am using png or jpg. Problem is: Loading the image data takes way too long (100s of ms on an iPad2).

I was wondering if someone knows the fastest way to load good-quality compressed image data on an iPad or similar? This could include switching to different image compression formats (?)

Here's what I've found:

• Loading jpg via the iOS implementation of libturbo-jpeg is faster than any way I found for png.

• If you split jpg images in two, you can parallel-decompress via GCD which almost cuts the load time in half. Still not enough!

• The PowerVR compressed PVRTC format can be loaded very quickly, but both compression ratio and image quality are way outside what I need...

• No idea how jpeg-2000 would perform, but it seems to be optimized for compression ratio rather than decoding speed.

Any ideas?? This must be a common problem for games or similar..

Are there any newer image formats (jpg is 1986!!) which have portable implementation, maybe slightly less compression than jpg, but decode much faster?

Answer 1

This library might help you out:

https://github.com/path/FastImageCache