Created
June 5, 2016 19:48
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UIImage extension for creating a new image with adjusted exposure
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extension UIImage { | |
/** | |
Returns a new `UIImage` with an adjusted exposure value. | |
- Parameter ev: The amount to adjust the exposure value. Negative for darker, positive for lighter. | |
- Returns: a new `UIImage` with an adjusted exposure value. | |
*/ | |
func imageWithAdjustedExposure(ev: Double) -> UIImage? { | |
guard let cgImage = self.CGImage else { return nil } | |
let filterName = "CIExposureAdjust" | |
guard let filter = CIFilter(name: filterName) else { | |
print("No filter with name: \(filterName).") | |
return nil | |
} | |
let inputImage = CoreImage.CIImage(CGImage: cgImage) | |
filter.setValue(inputImage, forKey: kCIInputImageKey) | |
filter.setValue(ev, forKey: kCIInputEVKey) | |
guard let filteredImage = filter.outputImage else { | |
print("No output image.") | |
return nil | |
} | |
let context = CIContext(options: nil) | |
return UIImage(CGImage: context.createCGImage(filteredImage, fromRect: filteredImage.extent)) | |
} | |
} |
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