我想使用查找表png（example）作为Swift中CIColorCube过滤器的颜色立方体数据。到目前为止，我尝试（和发现）的所有例子都是this example中计算颜色立方体的例子。
如何将png作为查找数据读取？
答案 0 :(得分：3)
我现在使用this和this项目来调整他们对Swift的Objective-C实现：
func colorCubeFilterFromLUT(imageName : NSString) -> CIFilter? {
let kDimension : UInt = 64
let lutImage = UIImage(named: imageName)!.CGImage
let lutWidth = CGImageGetWidth(lutImage!)
let lutHeight = CGImageGetHeight(lutImage!)
let rowCount = lutHeight / kDimension
let columnCount = lutWidth / kDimension
if ((lutWidth % kDimension != 0) || (lutHeight % kDimension != 0) || (rowCount * columnCount != kDimension)) {
NSLog("Invalid colorLUT %@", imageName);
return nil
}
let bitmap = self.createRGBABitmapFromImage(lutImage)
let size = Int(kDimension) * Int(kDimension) * Int(kDimension) * sizeof(Float) * 4
let data = UnsafeMutablePointer<Float>(malloc(UInt(size)))
var bitmapOffset : Int = 0
var z : UInt = 0
for (var row: UInt = 0; row < rowCount; row++)
{
for (var y: UInt = 0; y < kDimension; y++)
{
var tmp = z
for (var col: UInt = 0; col < columnCount; col++)
{
for (var x: UInt = 0; x < kDimension; x++) {
let alpha = Float(bitmap[Int(bitmapOffset)]) / 255.0
let red = Float(bitmap[Int(bitmapOffset+1)]) / 255.0
let green = Float(bitmap[Int(bitmapOffset+2)]) / 255.0
let blue = Float(bitmap[Int(bitmapOffset+3)]) / 255.0
var dataOffset = Int(z * kDimension * kDimension + y * kDimension + x) * 4
data[dataOffset] = red
data[dataOffset + 1] = green
data[dataOffset + 2] = blue
data[dataOffset + 3] = alpha
bitmapOffset += 4
}
z++
}
z = tmp
}
z += columnCount
}
let colorCubeData = NSData(bytesNoCopy: data, length: size, freeWhenDone: true)
// create CIColorCube Filter
var filter = CIFilter(name: "CIColorCube")
filter.setValue(colorCubeData, forKey: "inputCubeData")
filter.setValue(kDimension, forKey: "inputCubeDimension")
return filter
}
func createRGBABitmapFromImage(inImage: CGImage) -> UnsafeMutablePointer<Float> {
//Get image width, height
let pixelsWide = CGImageGetWidth(inImage)
let pixelsHigh = CGImageGetHeight(inImage)
// Declare the number of bytes per row. Each pixel in the bitmap in this
// example is represented by 4 bytes; 8 bits each of red, green, blue, and
// alpha.
let bitmapBytesPerRow = Int(pixelsWide) * 4
let bitmapByteCount = bitmapBytesPerRow * Int(pixelsHigh)
// Use the generic RGB color space.
let colorSpace = CGColorSpaceCreateDeviceRGB()
// Allocate memory for image data. This is the destination in memory
// where any drawing to the bitmap context will be rendered.
let bitmapData = malloc(CUnsignedLong(bitmapByteCount)) // bitmap
let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.PremultipliedFirst.rawValue)
// Create the bitmap context. We want pre-multiplied RGBA, 8-bits
// per component. Regardless of what the source image format is
// (CMYK, Grayscale, and so on) it will be converted over to the format
// specified here by CGBitmapContextCreate.
let context = CGBitmapContextCreate(bitmapData, pixelsWide, pixelsHigh, 8, UInt(bitmapBytesPerRow), colorSpace, bitmapInfo)
let rect = CGRect(x:0, y:0, width:Int(pixelsWide), height:Int(pixelsHigh))
// Draw the image to the bitmap context. Once we draw, the memory
// allocated for the context for rendering will then contain the
// raw image data in the specified color space.
CGContextDrawImage(context, rect, inImage)
// Now we can get a pointer to the image data associated with the bitmap
// context.
// var data = CGBitmapContextGetData(context)
// var dataType = UnsafeMutablePointer<Float>(data)
// return dataType
var convertedBitmap = malloc(UInt(bitmapByteCount * sizeof(Float)))
vDSP_vfltu8(UnsafePointer<UInt8>(bitmapData), 1, UnsafeMutablePointer<Float>(convertedBitmap), 1, vDSP_Length(bitmapByteCount))
free(bitmapData)
return UnsafeMutablePointer<Float>(convertedBitmap)
}
另见this回答。
答案 1 :(得分：1)
以为我会为Swift 3.0更新这个也适用于JPG和PNG的3D Color LUT
fileprivate func colorCubeFilterFromLUT(imageName : String) -> CIFilter? {
let size = 64
let lutImage = UIImage(named: imageName)!.cgImage
let lutWidth = lutImage!.width
let lutHeight = lutImage!.height
let rowCount = lutHeight / size
let columnCount = lutWidth / size
if ((lutWidth % size != 0) || (lutHeight % size != 0) || (rowCount * columnCount != size)) {
NSLog("Invalid colorLUT %@", imageName);
return nil
}
let bitmap = getBytesFromImage(image: UIImage(named: imageName))!
let floatSize = MemoryLayout<Float>.size
let cubeData = UnsafeMutablePointer<Float>.allocate(capacity: size * size * size * 4 * floatSize)
var z = 0
var bitmapOffset = 0
for _ in 0 ..< rowCount {
for y in 0 ..< size {
let tmp = z
for _ in 0 ..< columnCount {
for x in 0 ..< size {
let alpha = Float(bitmap[bitmapOffset]) / 255.0
let red = Float(bitmap[bitmapOffset+1]) / 255.0
let green = Float(bitmap[bitmapOffset+2]) / 255.0
let blue = Float(bitmap[bitmapOffset+3]) / 255.0
let dataOffset = (z * size * size + y * size + x) * 4
cubeData[dataOffset + 3] = alpha
cubeData[dataOffset + 2] = red
cubeData[dataOffset + 1] = green
cubeData[dataOffset + 0] = blue
bitmapOffset += 4
}
z += 1
}
z = tmp
}
z += columnCount
}
let colorCubeData = NSData(bytesNoCopy: cubeData, length: size * size * size * 4 * floatSize, freeWhenDone: true)
// create CIColorCube Filter
let filter = CIFilter(name: "CIColorCube")
filter?.setValue(colorCubeData, forKey: "inputCubeData")
filter?.setValue(size, forKey: "inputCubeDimension")
return filter
}
fileprivate func getBytesFromImage(image:UIImage?) -> [UInt8]?
{
var pixelValues: [UInt8]?
if let imageRef = image?.cgImage {
let width = Int(imageRef.width)
let height = Int(imageRef.height)
let bitsPerComponent = 8
let bytesPerRow = width * 4
let totalBytes = height * bytesPerRow
let bitmapInfo = CGImageAlphaInfo.premultipliedLast.rawValue | CGBitmapInfo.byteOrder32Little.rawValue
let colorSpace = CGColorSpaceCreateDeviceRGB()
var intensities = [UInt8](repeating: 0, count: totalBytes)
let contextRef = CGContext(data: &intensities, width: width, height: height, bitsPerComponent: bitsPerComponent, bytesPerRow: bytesPerRow, space: colorSpace, bitmapInfo: bitmapInfo)
contextRef?.draw(imageRef, in: CGRect(x: 0.0, y: 0.0, width: CGFloat(width), height: CGFloat(height)))
pixelValues = intensities
}
return pixelValues!
}