GPUImage memory usage - objective-c

Question

I noticed that the more I use GPUImage, the more memory my app takes over time (using Instruments to monitor memory use).
As an example, I use each filter in a different methods:
(UIImage*)ToonFilter:(UIImage*)theImage
{
GPUImageSmoothToonFilter *smoothToonFilter = [[GPUImageSmoothToonFilter alloc] init];
[smoothToonFilter setTexelHeight:0.0025];
[smoothToonFilter setTexelWidth:0.0025];
return [smoothToonFilter imageByFilteringImage:theImage];
}
(UIImage*)SketchFilter:(UIImage*)theImage
{
GPUImageSketchFilter *sketchFilter = [[GPUImageSketchFilter alloc] init];
[sketchFilter setTexelHeight:0.003];
[sketchFilter setTexelWidth:0.003];
return [sketchFilter imageByFilteringImage:theImage];
}
(UIImage*)PixellateFilter:(UIImage*)theImage
{
GPUImagePixellateFilter *pixellateFilter = [[GPUImagePixellateFilter alloc] init];
[pixellateFilter setFractionalWidthOfAPixel:0.01;
return [pixellateFilter imageByFilteringImage:theImage];
}
And this is how I use these filters (testImage is a UIImage):
testImage = [self SketchFilter:testImage];
testImage = [self PixellateFilter:testImage];
If I just cycle through these filters over and over, without doing anything else, the app takes more and more memory.
What am I doing wrong? How can I release the memory once I don't need it anymore?

Answer 1

You keep allocating new filters every time you call these functions. Create them once in your view controller etc and send them to your functions like the sample code below (as well as a GPUImagePicture). Also don't forget to call [removeAllTargets] on your filters, sometimes they do not get removed from memory when they have targets
(UIImage*)PixellateFilter:(UIImage*)theImage withPixellateFilter:(GPUImagePixellateFilter *) pixellateFilter andStaticPicture:(GPUImagePicture *)staticPicture
and also use [filter prepareForImageCapture] before getting UIImage from your filters
For example you can build your function like
(UIImage*)PixellateFilter:(UIImage*)theImage withPixellateFilter:(GPUImagePixellateFilter *) pixellateFilter andStaticPicture:(GPUImagePicture *)staticPicture{
[staticPicture removeAllTargets];
UIImage __block *imageToReturn;
[staticPicture addTarget:pixellateFilter];
[staticPicture processImageWithCompletionHandler:^{
[pixellateFilter prepareForImageCapture];
imageToReturn = [pixellateFilter imageFromCurrentlyProcessedOutput];
[pixellateFilter removeAllTargets];
pixellateFilter = nil;
}];
return imageToReturn;
}
I use GPUImageView for my application which allows you to use GPUImageFilters and GPUImagePictures directly without getting UIImage, you should definitely consider it