How control memory usage when applying CIFilters? - objective-c

Question

When I apply CIFilters to images the memory usage keeps growing and I don't know what to do.
I've tried everything I could:
using #autoreleasepool:
- (UIImage *)applySepiaToneTo:(UIImage *)img //Sepia
{
#autoreleasepool
{
CIImage *ciimageToFilter = [CIImage imageWithCGImage:img.CGImage];
CIFilter *sepia = [CIFilter filterWithName:#"CISepiaTone"
keysAndValues: kCIInputImageKey, ciimageToFilter,
#"inputIntensity", #1.0, nil];
return [self retrieveFilteredImageWithFilter:sepia];
}
}
- (UIImage *)retrieveFilteredImageWithFilter:(CIFilter *)filtro
{
#autoreleasepool
{
CIImage *ciimageFiltered = [filtro outputImage];
CGImageRef cgimg = [_context createCGImage:ciimageFiltered
fromRect:[ciimageFiltered extent]];
UIImage *filteredImage = [UIImage imageWithCGImage:cgimg];
CGImageRelease(cgimg);
return filteredImage;
}
}
I'm also downsizing the image to be filtered and doing the filtering in a background thread:
- (void)filterWasSelected:(NSNotification *)notification
{
self.darkeningView.alpha = 0.5;
self.darkeningView.userInteractionEnabled = YES;
[self.view bringSubviewToFront:self.darkeningView];
[self.activityIndic startAnimating];
[self.view bringSubviewToFront:self.activityIndic];
int indice = [notification.object intValue];
__block NSArray *returnObj;
__block UIImage *auxUiimage;
if(choosenImage.size.width == 1280 || choosenImage.size.height == 1280)
{
UIImageView *iv;
if(choosenImage.size.width >= choosenImage.size.height)
{
float altura = (320 * choosenImage.size.height)/choosenImage.size.width;
iv = [[UIImageView alloc] initWithFrame:CGRectMake(0,0,320,altura)];
iv.image = choosenImage;
}
else
{
float largura = (choosenImage.size.width * 320)/choosenImage.size.height;
iv = [[UIImageView alloc] initWithFrame:CGRectMake(0,0,largura,320)];
iv.image = choosenImage;
}
UIGraphicsBeginImageContextWithOptions(iv.bounds.size, YES, 0.0);
[iv.layer renderInContext:UIGraphicsGetCurrentContext()];
auxUiimage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
else
auxUiimage = choosenImage;
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
if(artisticCollection)
returnObj = [self.filterCoordinator setupFilterArtisticType:indice toImage:auxUiimage];
else
returnObj = [self.filterCoordinator setupFilterOldOrVintageType:indice toImage:auxUiimage];
dispatch_async(dispatch_get_main_queue(), ^{
self.darkeningView.alpha = 0.3;
self.darkeningView.userInteractionEnabled = NO;
[self.activityIndic stopAnimating];
[self.view bringSubviewToFront:stageBackground];
[self.view bringSubviewToFront:stage];
[self.view bringSubviewToFront:self.filtersContainerView];
[self.view bringSubviewToFront:self.framesContainerView];
[self.view bringSubviewToFront:self.colorsContainerView];
if(returnObj)
{
auxUiimage = [returnObj firstObject];
NSLog(#"filtered image width = %f and height = %f", auxUiimage.size.width, auxUiimage.size.height);
returnObj = nil;
choosenImageContainer.image = auxUiimage;
}
});
});
}
I've also tried creating the context using the contextWithEAGLContext method, nothing changed.
I've researched a lot including stack overflow and found nothing.
Until I place the image in the image view (the image comes from the photo album) I'm only using 23 mega of memory, when I apply a filter, the use jumps to 51 mega and does not comes down. If I continue to apply other filters the memory usage only grows.
There's no linking in my app, I've checked in Instruments.
Also the bringSubviewToFront methods are not responsible, I've checked.
It's in the creation of the CIImage followed by the creation of the CIFilter object.
I know that in the process of applying the filter data is loaded into memory, but how to clean the memory after applying the filter?
Is there any secret that I'm not aware of?? Please help