iOS: How to efficiently blur an image?

问题

I have an image that is stored a RGBA format in memory. I've written a blur routine that works fine for small blur radii, however big ones like 16 point take forever. Is there an efficient way using CoreImage etc to blur an image? Will using it cause any loss in image quality?

回答1:

Have you tried the built-in CIGaussianBlur? One thing you could do to improve your performance is the following:

1. Use the CILanczosScaleTransform filter to scale-down your image.
2. Perform a low-radius blur using CIGaussianBlur.
3. Use CILanczosScaleTransform to scale-up your image.

来源：https://stackoverflow.com/questions/28710332/ios-how-to-efficiently-blur-an-image