how to make a C4Image animate to black and white

C4WorkSpace.m

#import "C4WorkSpace.h"

C4Image *myImage;

@implementation C4WorkSpace

-(void)setup {
    myImage = [C4Image imageNamed:@"C4Sky.png"];
    myImage.center = CGPointMake(384, 512);
    [self.canvas addImage:myImage];
}

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    myImage.animationDuration = 2.0f;
    [myImage colorControlSaturation:0 brightness:0 contrast:1];
}

@end