Swift Image Processing

This project contains swift playgrounds that demonstrate how to do pixel operations in swift.

Swift4 : checkout master branch
Swift3.x : checkout syntax/swift3.x branch
Swift2.x : checkout syntax/swift2.x branch

Thanks to RGBAImage

http://mhorga.org/2015/10/19/image-processing-in-ios-part-3.html
This articles help me a lot!

Convert UIImage to RGBA Image

RGBAImage has pixels flat memory. You can access pixels with index directly.

Contrast

This is example for pixel operation

let rgba = RGBAImage(image: UIImage(named: "monet")!)!


var totalR = 0
var totalG = 0
var totalB = 0

rgba.process { (pixel) -> Pixel in
    totalR += Int(pixel.R)
    totalG += Int(pixel.G)
    totalB += Int(pixel.B)
    return pixel
}

let pixelCount = rgba.width * rgba.height
let avgR = totalR / pixelCount
let avgG = totalG / pixelCount
let avgB = totalB / pixelCount



func contrast(_ image: RGBAImage) -> RGBAImage {
    
    image.process { (pixel) -> Pixel in
        var pixel = pixel
        let deltaR = Int(pixel.R) - avgR
        let deltaG = Int(pixel.G) - avgG
        let deltaB = Int(pixel.B) - avgB
        pixel.R = UInt8(max(min(255, avgR + 3 * deltaR), 0)) //clamp
        pixel.G = UInt8(max(min(255, avgG + 3 * deltaG), 0))
        pixel.B = UInt8(max(min(255, avgB + 3 * deltaB), 0))
        
        return pixel
    }
    return image
}

let newImage = contrast(rgba).toUIImage()

Grab color space

Grab Red component

func grabR(_ image: RGBAImage) -> RGBAImage {
    var outImage = image
    outImage.process { (pixel) -> Pixel in
        var pixel = pixel
        pixel.R = pixel.R
        pixel.G = 0
        pixel.B = 0
        return pixel
    }
    return outImage
}

Grab Green component

func grabG(_ image: RGBAImage) -> RGBAImage {
    var outImage = image
    outImage.process { (pixel) -> Pixel in
        var pixel = pixel
        pixel.R = 0
        pixel.G = pixel.G
        pixel.B = 0
        return pixel
    }
    return outImage
}

Grab Blue component

func grabB(_ image: RGBAImage) -> RGBAImage {
    var outImage = image
    outImage.process { (pixel) -> Pixel in
        var pixel = pixel
        pixel.R = 0
        pixel.G = 0
        pixel.B = pixel.B
        return pixel
    }
    return outImage
}

Compose RGB Color components

public static func composite(_ rgbaImageList: RGBAImage...) -> RGBAImage {
        let result : RGBAImage = RGBAImage(width:rgbaImageList[0].width, height: rgbaImageList[0].height)
        for y in 0..<result.height {
            for x in 0..<result.width {
                
                let index = y * result.width + x
                var pixel = result.pixels[index]
                
                for rgba in rgbaImageList {
                    let rgbaPixel = rgba.pixels[index]
                    pixel.Rf = pixel.Rf + rgbaPixel.Rf
                    pixel.Gf = pixel.Gf + rgbaPixel.Gf
                    pixel.Bf = pixel.Bf + rgbaPixel.Bf
                }
                
                result.pixels[index] = pixel
            }
        }
        return result
    }

RGB to Gray

public static func gray5(_ image: RGBAImage) -> RGBAImage {
        var outImage = image
        outImage.process { (pixel) -> Pixel in
            var pixel = pixel
            let result = sqrt(pow(pixel.Rf, 2) + pow(pixel.Rf, 2) + pow(pixel.Rf, 2))/sqrt(3.0)
            pixel.Rf = result
            pixel.Gf = result
            pixel.Bf = result
            return pixel
        }
        return outImage
}
let rgba5 = RGBAImage(image: UIImage(named: "monet")!)!
gray5(rgba5).toUIImage()

Refactoring Split Color Space

public static func splitRGB(_ rgba: RGBAImage) -> (ByteImage, ByteImage, ByteImage) {
    let R = ByteImage(width: rgba.width, height: rgba.height)
    let G = ByteImage(width: rgba.width, height: rgba.height)
    let B = ByteImage(width: rgba.width, height: rgba.height)
    
    rgba.enumerate { (index, pixel) -> Void in
        
        R.pixels[index] = pixel.R.toBytePixel()
        G.pixels[index] = pixel.G.toBytePixel()
        B.pixels[index] = pixel.B.toBytePixel()
    }
    
    return (R, G, B)
}

ByteImage has only one color component.

Images ADD, SUB, MUL, DIV

public static func op(_ functor : (Double, Double) -> Double, rgbaImage1: RGBAImage, rgbaImage2: RGBAImage) -> RGBAImage {
    let result : RGBAImage = RGBAImage(width:rgbaImage1.width, height: rgbaImage1.height)
    for y in 0..<result.height {
        for x in 0..<result.width {
            
            let index = y * result.width + x
            var pixel = result.pixels[index]
            
            let rgba1Pixel = rgbaImage1.pixels[index]
            let rgba2Pixel = rgbaImage2.pixels[index]
            
            
            pixel.Rf = functor(rgba1Pixel.Rf, rgba2Pixel.Rf)
            pixel.Gf = functor(rgba1Pixel.Gf, rgba2Pixel.Gf)
            pixel.Bf = functor(rgba1Pixel.Bf, rgba2Pixel.Bf)
            
            result.pixels[index] = pixel
        }
    }
    return result   
}

public static func add(rgba1: RGBAImage, _ rgba2: RGBAImage) -> RGBAImage {
    return op((+), rgbaImage1: rgba1, rgbaImage2: rgba2)
}

Blending

public static func blending(_ img1: RGBAImage, _ img2: RGBAImage, alpha: Double) -> RGBAImage {
    let result : RGBAImage = RGBAImage(width:img1.width, height: img1.height)
    for y in 0..<result.height {
        for x in 0..<result.width {
            
            let index = y * result.width + x
            var pixel = result.pixels[index]
            
            let pixel1 = img1.pixels[index]
            let pixel2 = img2.pixels[index]
            
            
            pixel.Rf = alpha * pixel1.Rf + (1.0 - alpha) * pixel2.Rf
            pixel.Gf = alpha * pixel1.Gf + (1.0 - alpha) * pixel2.Gf
            pixel.Bf = alpha * pixel1.Bf + (1.0 - alpha) * pixel2.Bf
            
            result.pixels[index] = pixel
        }
    }
    return result
}

Brightness

public static func brightness(_ img1: RGBAImage, contrast: Double, brightness: Double) -> RGBAImage {
    let result : RGBAImage = RGBAImage(width:img1.width, height: img1.height)
    for y in 0..<result.height {
        for x in 0..<result.width {
            
            let index = y * result.width + x
            var pixel = result.pixels[index]
            
            let pixel1 = img1.pixels[index]
            
            pixel.Rf = pixel1.Rf * contrast + brightness
            pixel.Gf = pixel1.Gf * contrast + brightness
            pixel.Bf = pixel1.Bf * contrast + brightness
            
            result.pixels[index] = pixel
        }
    }
    return result
}

Convolution

public static func convolution(_ image: ByteImage, mask: Array2D<Double>) -> ByteImage {
    var image = image
    let height = image.height
    let width  = image.width
    
    let maskHeight = mask.rowCount()
    let maskWidth  = mask.colCount()
    
    for y in 0..<height - maskHeight + (maskHeight-1)/2 {
        for x in 0..<width - maskWidth + (maskWidth-1)/2 {
            var v = 0.0
            if (y+maskHeight > height) || (x+maskWidth) > width {
                continue
            }
            
            for my in 0..<maskHeight {
                for mx in 0..<maskWidth {
                    let tmp = mask[my, mx]
                    v = v + (image.pixel(x+mx, y+my)!.Cf * tmp)
                }
            }
            
            v = clamp(v, lower: 0.0, upper: 1.0)
            print(v)
            let pixel = BytePixel(value: v)
            let xx = x+(maskWidth-1)/2
            let yy = y+(maskHeight-1)/2
            image.setPixel(xx, yy, pixel)
        }
    }
    return image
}

Sharpening

let m1 = Array2D(cols:3, rows:3,
    [ 0.0/5.0, -1.0/5.0, 0.0/5.0,
     -1.0/5.0,  9.0/5.0,-1.0/5.0,
      0.0/5.0, -1.0/5.0, 0.0/5.0])
ImageProcess.convolution(R.clone(), mask: m1).toUIImage()

Bluring

let m2 = Array2D(cols: 3, rows: 3,
    [
         1.0/9.0, 1.0/9.0, 1.0/9.0,
         1.0/9.0, 1.0/9.0, 1.0/9.0,
         1.0/9.0, 1.0/9.0, 1.0/9.0,
    ]
)
ImageProcess.convolution(R.clone(), mask: m2).toUIImage()

MIT License

The MIT License

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

skyfe79/SwiftImageProcessing

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