Fastest way to apply a Gaussian Blur on a image without Core-Animation

Question

I need to apply a Gaussian Blur to a NSImage.
Since this image changes a lot over the lifetime of the application, the operation should be quick so that the UI stays somewhat responsive.

Unfortunately, I have not found a satisfying solution for this problem.

So basically, I've tried three things:

• Core Animation (Not an option)
• CIFilter (Terribly slow, 1s or more per operation)
• GPUImage (Also terribly slow, 1s or more per operation)

What would be the fastest way of applying a Gaussian Blur (or any filter, for that matter) to a NSImage?

---

CIFilter

CIImage *imageToBlur = [CIImage imageWithData:[backgroundImage TIFFRepresentation]];
CIFilter *gaussianBlurFilter = [CIFilter filterWithName: @"CIGaussianBlur"];
[gaussianBlurFilter setValue:imageToBlur forKey:kCIInputImageKey];
[gaussianBlurFilter setValue:[NSNumber numberWithFloat: 10] forKey: @"inputRadius"];

NSCIImageRep *rep = [NSCIImageRep imageRepWithCIImage:[gaussianBlurFilter valueForKey:kCIOutputImageKey]];
NSImage *nsImage = [[NSImage alloc] initWithSize:rep.size];
[nsImage addRepresentation:rep];

_backgroundImage = nsImage;

---

GPUImage

GPUImagePicture *stillImageSource = [[GPUImagePicture alloc] initWithImage:backgroundImage];
GPUImageGaussianBlurFilter *gaussianBlurFilter = [[GPUImageGaussianBlurFilter alloc] init];
gaussianBlurFilter.blurRadiusInPixels = 10.0;

[stillImageSource addTarget:gaussianBlurFilter];
[stillImageSource processImage];

_backgroundImage = [gaussianBlurFilter imageFromCurrentlyProcessedOutput];