A filthy example of working with images and filters. This code currently shows a work-in-progress overhaul of C4Image.

C4WorkSpace.m

//
//  C4WorkSpace.m
//
//  Created by Travis Kirton.
//

#import "C4WorkSpace.h"

@implementation C4WorkSpace {
    C4Image *img1, *img2, *img3, *img4, *img5, *img6;
}

-(void)setup {
    CGPoint orig = CGPointMake(0,320);
    img1 = [C4Image imageNamed:@"C4Sky"];
    img2 = [C4Image imageWithImage:img1];
    img2.origin = orig; orig.y += 320;
    img2.animationDuration = 1.0f;
    img2.animationOptions = AUTOREVERSE | REPEAT;
    [img2 colorMatrix:C4RED bias:0.05f];
    img3 = [[C4Image alloc] initWithCGImage:img1.CGImage];
    img3.origin = orig; orig.x = 400; orig.y = 0;
    img4 = [[C4Image alloc] initWithUIImage:img2.UIImage];
    img4.origin = orig; orig.y += 320;
    [img2 showOriginalImage];
    img5 = [[C4Image alloc] initWithUIImage:[UIImage imageWithCIImage:img4.CIImage]];
    img5.origin = orig; orig.y += 320;
    [img4 hueAdjust:0.5f];
    [self.canvas addObjects:@[img1,img2,img3,img4,img5]];

    [self listenFor:@"CIHueAdjustComplete" fromObject:img4 andRunMethod:@"test"];
}

-(void)test {
    img6 = [[C4Image alloc] initWithUIImage:[UIImage imageWithCGImage:img4.filteredImage]];
    img6.origin = CGPointMake(img5.origin.x, img5.origin.y + 320);
    img6.animationDuration = 1.0f;
    [img6 colorInvert];
    [self.canvas addImage:img6];
}

@end