How to filter images using Core Image and CIFilter

Paul Hudson    September 15th 2016    @twostraws

Core Image is the one of the most powerful frameworks available to iOS developers: it makes hardware-accelerated image manipulation ridiculously easy, which means you get to add powerful graphical effects to your apps and games with very little work.

Most of the work is done by choosing the right CIFilter. Apple's official documentation goes into great detail about the various filters you can use, and you can also read Hacking with Swift project 13 for a hands-on tutorial showing off various effects. The code below applies a 50% sepia tone effect to an image:

let inputImage = UIImage(named: "taylor-swift")!
let context = CIContext(options: nil)

if let currentFilter = CIFilter(name: "CISepiaTone") {
    let beginImage = CIImage(image: inputImage)
    currentFilter.setValue(beginImage, forKey: kCIInputImageKey)
    currentFilter.setValue(0.5, forKey: kCIInputIntensityKey)

    if let output = currentFilter.outputImage {
        if let cgimg = context.createCGImage(output, from: output.extent) {
            let processedImage = UIImage(cgImage: cgimg)
            // do something interesting with the processed image
        }
    }
}

Available from iOS 5.0 – see Hacking with Swift tutorial 13

Did this solution work for you? Please pass it on!

Tweet

Other people are reading…

• How to play sounds using AVAudioPlayer
• How to play videos using AVPlayerViewController
• UIImageWriteToSavedPhotosAlbum(): how to write to the iOS photo album
• How to create a QR code
• How to read the average color of a UIImage using CIAreaAverage

About the Swift Knowledge Base

This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.