UIImage color correction - ios

Question

I am using AVFoundation to play a video by creating a CGImage from the AVFoundation callback, creating a UIImage from the CGImage and then displaying the UIImage in a UIImageView.
I want to apply some color correction to the images before I display them on the screen. What is the best way to colorize the images I'm getting?
I tried using the CIFilters, but that requires me to first create a CIImage from AVFoundation, then colorise it, then create a CGImage and then create a UIImage, and I'd rather avoid the extra step of creating the CIImage if possible.
Additionally, it doesn't seem like the performance of the CIFilters is fast enough - at least not when also having to create the additional CIImage. Any suggestions for a faster way to go about doing this?
Thanks in advance.

Answer 1

It seems that using an EAGLContext instead of a standard CIContext is the answer. That gives fast enough performance in creating the colorized images for my needs.
Simple code example here:
On Init:
NSMutableDictionary *options = [[NSMutableDictionary alloc] init];
[options setObject: [NSNull null] forKey: kCIContextWorkingColorSpace];
m_EAGLContext = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];
m_CIContext = [CIContext contextWithEAGLContext:m_EAGLContext options:options];
Set the color:
-(void)setColorCorrection:(UIColor*)color
{
CGFloat r,g,b,a;
[color getRed:&r green:&g blue:&b alpha:&a];
CIVector *redVector = [CIVector vectorWithX:r Y:0 Z:0];
CIVector *greenVector = [CIVector vectorWithX:0 Y:g Z:0];
CIVector *blueVector = [CIVector vectorWithX:0 Y:0 Z:b];
m_ColorFilter = [CIFilter filterWithName:#"CIColorMatrix"];
[m_ColorFilter setDefaults];
[m_ColorFilter setValue:redVector forKey:#"inputRVector"];
[m_ColorFilter setValue:greenVector forKey:#"inputGVector"];
[m_ColorFilter setValue:blueVector forKey:#"inputBVector"];
}
On each video frame:
CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
CVPixelBufferLockBaseAddress(pixelBuffer, 0);
CGImageRef cgImage = nil;
CIImage *ciImage = [CIImage imageWithCVPixelBuffer:pixelBuffer];
[m_ColorFilter setValue:ciImage forKey:kCIInputImageKey];
CIImage *adjustedImage = [m_ColorFilter valueForKey:kCIOutputImageKey];
cgImage = [m_CIContext createCGImage:adjustedImage fromRect:ciImage.extent];