ImageProcessing.swift

var backgroundColor: [UInt8] = [0, 0, 0, 0]

let GaussianBlurKernel: [Int16] =
[   1, 4, 6, 4, 1,
    4, 16, 24, 16, 4,
    6, 24, 36, 24, 6,
    4, 16, 24, 16, 4,
    1, 4, 6, 4, 1
]

let EmbossKernel: [Int16] =
[
    -2, 0, 0,
    0, 1, 0,
    0, 0, 2
];

let EdgeDetectionKernel: [Int16] = [
    -1, -1, -1,
     0, 0, 0,
    1, 1, 1
];

func embossImage(image: UIImage, bias: Int) -> UIImage {
    var inputBuffer = createInputBuffer(fromImage: image)
    var outputBuffer = createOutputBuffer(fromInputBuffer: inputBuffer)
    convolve(&inputBuffer, outputBuffer: &outputBuffer, kernel:EmbossKernel, withBias: Int32(bias))
    return createImageFromBuffer(outputBuffer)
}

func detectEdge(image: UIImage, bias: Int) -> UIImage {
    var inputBuffer = createInputBuffer(fromImage: image)
    var outputBuffer = createOutputBuffer(fromInputBuffer: inputBuffer)
    convolve(&inputBuffer, outputBuffer: &outputBuffer, kernel: EdgeDetectionKernel, withBias: Int32(bias))
    return createImageFromBuffer(outputBuffer)
}

func blurImage(image: UIImage, blurRadius: Int) -> UIImage {
    var inputBuffer = createInputBuffer(fromImage: image)
    var outputBuffer = createOutputBuffer(fromInputBuffer: inputBuffer)
    boxConvolve(&inputBuffer, outputBuffer: &outputBuffer, inputRadius: blurRadius)
    return createImageFromBuffer(outputBuffer)
}

func tentBlur(image: UIImage, blurRadius: Int) -> UIImage {
    var inputBuffer = createInputBuffer(fromImage: image)
    var outputBuffer = createOutputBuffer(fromInputBuffer: inputBuffer)
    boxConvolve(&inputBuffer, outputBuffer: &outputBuffer, inputRadius: blurRadius)
    return createImageFromBuffer(outputBuffer)
}


func createInputBuffer(fromImage image: UIImage) -> vImage_Buffer {
    let cgImage = image.CGImage!
    
    let dataProvider = CGImageGetDataProvider(cgImage)!
    
    let data = CGDataProviderCopyData(dataProvider)!
    
    let bytes = CFDataGetBytePtr(data)
    
    let inputBuffer = vImage_Buffer(data: UnsafeMutablePointer<Void>(bytes), height: vImagePixelCount(CGImageGetHeight(cgImage)), width: vImagePixelCount(CGImageGetWidth(cgImage)), rowBytes: CGImageGetBytesPerRow(cgImage))
    return inputBuffer
}

func createOutputBuffer(fromInputBuffer inputBuffer: vImage_Buffer) -> vImage_Buffer {
    let size = inputBuffer.rowBytes * Int(inputBuffer.height) * 8
    let pixelBuffer = UnsafeMutablePointer<Void>.alloc(size)
    
    let outputBuffer = vImage_Buffer(data: pixelBuffer, height: inputBuffer.height, width: inputBuffer.width, rowBytes: inputBuffer.rowBytes)
    return outputBuffer
}

func convolve(inputBuffer: UnsafeMutablePointer<vImage_Buffer>,
             outputBuffer: UnsafeMutablePointer<vImage_Buffer>,
                   kernel:[Int16],
            withBias bias: Int32) {
        var kernelPointer = kernel
                
        vImageConvolveWithBias_ARGB8888(inputBuffer, outputBuffer, nil, 0, 0, &kernelPointer, 3, 3, 1, bias, backgroundColor, UInt32(kvImageBackgroundColorFill))
}

func tentConvolve(inputBuffer: UnsafeMutablePointer<vImage_Buffer>,
    outputBuffer: UnsafeMutablePointer<vImage_Buffer>,
    inputRadius: Int)
{
    var color: [UInt8] = [1, 0, 0, 1]
    var radius = UInt32(floor((Double(inputRadius) * 3 * sqrt(2 * M_PI) / 4 + 0.5) / 2))
    
    radius |= 1; // force radius to be odd so that the three box-blur methodology works.

    vImageTentConvolve_ARGB8888(inputBuffer, outputBuffer, nil, 0, 0, radius, radius, &color, UInt32(kvImageBackgroundColorFill))
}

func boxConvolve(inputBuffer: UnsafeMutablePointer<vImage_Buffer>,
    outputBuffer: UnsafeMutablePointer<vImage_Buffer>,
    inputRadius: Int)
{
    
    var radius = UInt32(floor((Double(inputRadius) * 3 * sqrt(2 * M_PI) / 4 + 0.5) / 2))
    
    radius |= 1; // force radius to be odd so that the three box-blur methodology works.
    
    vImageBoxConvolve_ARGB8888(inputBuffer, outputBuffer, nil, 0, 0, radius, radius, &backgroundColor, UInt32(kvImageBackgroundColorFill))
}

func createImageFromBuffer(buffer: vImage_Buffer) -> UIImage
{
    let colorSpace = CGColorSpaceCreateDeviceRGB()
    
    let context = CGBitmapContextCreate(buffer.data, Int(buffer.width), Int(buffer.height), 8, buffer.rowBytes, colorSpace, CGImageAlphaInfo.PremultipliedLast.rawValue)
    
    let cgImage = CGBitmapContextCreateImage(context)!
    
    let image = UIImage(CGImage: cgImage)
    return image
}


let image = UIImage(named: "CTT.png")!

blurImage(image, blurRadius: 10)
embossImage(image, bias: 12)
detectEdge(image, bias: 10)
tentBlur(image, blurRadius: 10)