Apply CIFilter to a CALayer #CoreImage #image-manipulation #ios

cifilter_calayer.m

// SIMPLE
// Note: Can convert to UIImage but there's no way to go to CGImage.
CIImage *newImg = [[CIImage imageWithCGImage:img.CGImage] imageByApplyingFilter:@"CIColorMonochrome"
                                                               withInputParameters:@{kCIInputColorKey: ciCol}];


// EXTENDED
CIContext *ctx = [CIContext contextWithOptions:nil];
CIFilter *filter = [CIFilter filterWithName:@"CIColorMonochrome"];
CIColor *color = [CIColor colorWithRed:pitchTilt green:rollTilt blue:1.0 alpha:1.0];
[filter setDefaults];
[filter setValue:[CIImage imageWithCGImage:img.CGImage] forKey:kCIInputImageKey];
[filter setValue:color forKey:kCIInputColorKey];
CGImageRef cgImg = [ctx createCGImage:filter.outputImage fromRect:filter.outputImage.extent];
static CALayer *l;
if (!l) {
    l = [CALayer layer];
    l.frame = CGRectMake(0, 0, filter.outputImage.extent.size.width/2.0, filter.outputImage.extent.size.height/2.0);
    [_instrumentPanel.layer addSublayer:l];
    l.contentsScale = 2.0;
}
l.contents = (__bridge id)(cgImg);