使用 vImageMatrixMultiply_ARGB8888 将颜色矩阵滤镜应用于 UIImage，就像 CIColorMatrix 一样
Apply color matrix filter to UIImage using vImageMatrixMultiply_ARGB8888 like does CIColorMatrix
我正在尝试构建一个 swift 函数，以使用 Accellerate 框架的 vImageMatrixMultiply_ARGB8888 将颜色矩阵滤镜应用于图像。
我以前能够使用 CIFilter CIColorMatrix.
将颜色矩阵应用于图像
let ciimage = CIImage(image: image)!
let colorMatrix = CIFilter(name: "CIColorMatrix")!
colorMatrix.setDefaults()
colorMatrix.setValue(ciimage, forKey: "inputImage")
colorMatrix.setValue(CIVector(x: 1.9692307692307693, y: 0, z: 0, w: 0), forKey: "inputRVector")
colorMatrix.setValue(CIVector(x: 0, y: 2.226086956521739, z: 0, w: 0), forKey: "inputGVector")
colorMatrix.setValue(CIVector(x: 0, y: 0, z: 2.585858585858586, w: 0), forKey: "inputBVector")
colorMatrix.setValue(CIVector(x: 0, y: 0, z: 0, w: 1), forKey: "inputAVector")
return UIImage(ciImage: colorMatrix.outputImage!)
RotatioMatrix used in vImageMatrixMultiply_ARGB8888 use same values of input vectors of CIFilter.
rotationMatrix = [1.9692307692307693, 0, 0, 0
0, 2.226086956521739, 0, 0,
0, 0, 2.585858585858586, 0,
0, 0, 0, 1].map {
return Int16(Float([=12=]) * Float(divisor)) // divisor = 256
}
以下代码不会产生与上面 CIFilter 中相同的结果。
private func rgbAdjustmentWithMatrix(image sourceImage: UIImage, rotationMatrix: [Int16]) -> UIImage? {
guard
let cgImage = sourceImage.cgImage,
let sourceImageFormat = vImage_CGImageFormat(cgImage: cgImage),
let rgbDestinationImageFormat = vImage_CGImageFormat(
bitsPerComponent: 8,
bitsPerPixel: 32,
colorSpace: CGColorSpaceCreateDeviceRGB(),
bitmapInfo: CGBitmapInfo(rawValue: CGImageAlphaInfo.first.rawValue),
renderingIntent: .defaultIntent) else {
print("Unable to initialize cgImage or colorSpace.")
return nil
}
guard
let sourceBuffer = try? vImage_Buffer(cgImage: cgImage),
var rgbDestinationBuffer = try? vImage_Buffer(width: Int(sourceBuffer.width),
height: Int(sourceBuffer.height),
bitsPerPixel: rgbDestinationImageFormat.bitsPerPixel) else {
print("Unable to initialize source buffer or destination buffer.")
return nil
}
defer {
sourceBuffer.free()
rgbDestinationBuffer.free()
}
do {
let toRgbConverter = try vImageConverter.make(sourceFormat: sourceImageFormat, destinationFormat: rgbDestinationImageFormat)
try toRgbConverter.convert(source: sourceBuffer, destination: &rgbDestinationBuffer)
} catch {
print("Unable to initialize converter or unable to convert.")
return nil
}
guard var resultBuffer = try? vImage_Buffer(width: Int(sourceBuffer.width),
height: Int(sourceBuffer.height),
bitsPerPixel: rgbDestinationImageFormat.bitsPerPixel) else {
print("Unable to initialize result buffer.")
return nil
}
defer {
resultBuffer.free()
}
var error: vImage_Error
let divisor: Int32 = 256
let preBias = [Int16](repeating: -256, count: 4)
let postBias = [Int32](repeating: 256 * divisor, count: 4)
error = vImageMatrixMultiply_ARGB8888(&rgbDestinationBuffer,
&resultBuffer,
rotationMatrix,
divisor,
preBias,
postBias,
0)
guard error == kvImageNoError else { return nil }
if let cgImage = try? resultBuffer.createCGImage(format: rgbDestinationImageFormat) {
return UIImage(cgImage: cgImage)
} else {
return nil
}
}
可能是颜色 space 的问题？或者 vImageMatrixMultiply_ARGB8888 输入矩阵与 CIFilter 输入矩阵不同？
更新
因此，看起来 vImageMatrixMultiply_ARGB8888 需要以下顺序的值：
let rotationMatrix = [
1, 0, 0, 0, // A
0, 1.9692307692307693, 0, 0, // R
0, 0, 2.226086956521739, 0, // G
0, 0, 0, 2.585858585858586 // B
].map { return Int16([=10=] * Float(divisor)) } // divisor = 0x1000
这与隐含 BGRA 的 Apple 示例代码不一致。可能该矩阵原本打算与不同的 pixelBuffer 格式一起使用 - 或者其他一些问题。
我相信您遇到的另一个问题 运行 是 CIFilter 使用默认的 CIContext。当我 运行 得到一个 linearSRGB workingColorSpace.
let context = CIContext()
print(context.workingColorSpace ?? "")
输出：
<CGColorSpace 0x7fe4abd06d30> (kCGColorSpaceICCBased; kCGColorSpaceModelRGB; sRGB Linear)
因此，您可以将 CGColorSpaceCreateDeviceRGB() 指定为 CIFilter 的 CIContext workingColorSpace，或者在 vImage 用法中将 rgbDestinationImageFormat colorSpace 设置为 .linearSRGB。在这个和更正后的矩阵顺序之间，我相信你的输出图像现在会匹配。
// error handling removed for brevity
let ciImage = CIImage(cgImage: cgImage)
let colorMatrix = CIFilter(name: "CIColorMatrix")!
colorMatrix.setDefaults()
colorMatrix.setValue(ciImage, forKey: "inputImage")
colorMatrix.setValue(CIVector(x: 1.9692307692307693, y: 0, z: 0, w: 0), forKey: "inputRVector")
colorMatrix.setValue(CIVector(x: 0, y: 2.226086956521739, z: 0, w: 0), forKey: "inputGVector")
colorMatrix.setValue(CIVector(x: 0, y: 0, z: 2.585858585858586, w: 0), forKey: "inputBVector")
colorMatrix.setValue(CIVector(x: 0, y: 0, z: 0, w: 1), forKey: "inputAVector")
let context = CIContext(options: [.workingColorSpace : CGColorSpaceCreateDeviceRGB()]) // without this, colorSpace defaults to linearSRGB
return context.createCGImage(colorMatrix.outputImage!, from: rect)!
在这种情况下，可能不需要预先和 post 偏差，除非您有其他原因这样做。
最后，您可能会受益于更大的除数。虽然像素数据是每通道 8 位，但累加器是 32 位，矩阵值是 16 位。大多数参考代码使用 0x1000 (4096) 的除数。
func rgbAdjustmentWithMatrix(image sourceImage: NSImage, rotationMatrix: [Int16]) -> CGImage? {
var rect = CGRect(x: 0, y: 0, width: sourceImage.size.width, height: sourceImage.size.height)
guard
let cgImage = sourceImage.cgImage(forProposedRect: &rect, context: nil, hints: nil),
let sourceImageFormat = vImage_CGImageFormat(cgImage: cgImage),
let rgbDestinationImageFormat = vImage_CGImageFormat(
bitsPerComponent: 8,
bitsPerPixel: 32,
colorSpace: CGColorSpaceCreateDeviceRGB(),
// can match CIFilter default with this:
// colorSpace: CGColorSpace(name: CGColorSpace.linearSRGB)!,
bitmapInfo: CGBitmapInfo(rawValue: CGImageAlphaInfo.first.rawValue),
renderingIntent: .defaultIntent)
else {
print("Unable to initialize cgImage or colorSpace.")
return nil
}
guard
var sourceBuffer = try? vImage_Buffer(cgImage: cgImage),
var rgbDestinationBuffer = try? vImage_Buffer(width: Int(sourceBuffer.width),
height: Int(sourceBuffer.height),
bitsPerPixel: rgbDestinationImageFormat.bitsPerPixel)
else {
fatalError("Error initializing source and destination buffers.")
}
defer {
sourceBuffer.free()
rgbDestinationBuffer.free()
}
do {
let toRgbConverter = try vImageConverter.make(sourceFormat: sourceImageFormat, destinationFormat: rgbDestinationImageFormat)
try toRgbConverter.convert(source: sourceBuffer, destination: &rgbDestinationBuffer)
} catch {
fatalError(error.localizedDescription)
}
let divisor: Int32 = 0x1000 // matrix values are 16 bit and accumulator is 32 bit
// 4096 gives us decent overhead for the matrix operation
// 12-bit color
let preBias: [Int16] = [0, 0, 0, 0] // or simply pass nil
let postBias: [Int32] = [0, 0, 0, 0] // or simply pass nil
let error = vImageMatrixMultiply_ARGB8888(&rgbDestinationBuffer,
&rgbDestinationBuffer,
rotationMatrix,
divisor,
preBias,
postBias,
vImage_Flags(kvImageNoFlags))
if error != kvImageNoError { print("Error: \(error)") }
let result = try? rgbDestinationBuffer.createCGImage(format: rgbDestinationImageFormat)
return result
}
上一个答案
查看您的代码和输出图像，我相信您将红色和蓝色系数颠倒了。如果是这样，您将像这样填充 vImage 矩阵：
rotationMatrix = [2.585858585858586, 0, 0, 0 // b
0, 2.226086956521739, 0, 0, // g
0, 0, 1.9692307692307693, 0, // r
0, 0, 0, 1].map { // a
return Int16(Float([=15=]) * Float(divisor)) // divisor = 256
}
这与 desaturating a selected portion of an image 的 Apple vImage 示例代码一致。
let desaturationMatrix = [
0.0722, 0.0722, 0.0722, 0,
0.7152, 0.7152, 0.7152, 0,
0.2126, 0.2126, 0.2126, 0,
0, 0, 0, 1
].map {
return Int16([=16=] * Float(divisor))
}
请注意，coefficients for Rec709 到 Luma 的转换为：
Y = R * 0.2126 + G * 0.7152 + B * 0.0722
我正在尝试构建一个 swift 函数，以使用 Accellerate 框架的 vImageMatrixMultiply_ARGB8888 将颜色矩阵滤镜应用于图像。 我以前能够使用 CIFilter CIColorMatrix.
将颜色矩阵应用于图像 let ciimage = CIImage(image: image)!
let colorMatrix = CIFilter(name: "CIColorMatrix")!
colorMatrix.setDefaults()
colorMatrix.setValue(ciimage, forKey: "inputImage")
colorMatrix.setValue(CIVector(x: 1.9692307692307693, y: 0, z: 0, w: 0), forKey: "inputRVector")
colorMatrix.setValue(CIVector(x: 0, y: 2.226086956521739, z: 0, w: 0), forKey: "inputGVector")
colorMatrix.setValue(CIVector(x: 0, y: 0, z: 2.585858585858586, w: 0), forKey: "inputBVector")
colorMatrix.setValue(CIVector(x: 0, y: 0, z: 0, w: 1), forKey: "inputAVector")
return UIImage(ciImage: colorMatrix.outputImage!)
RotatioMatrix used in vImageMatrixMultiply_ARGB8888 use same values of input vectors of CIFilter.
rotationMatrix = [1.9692307692307693, 0, 0, 0
0, 2.226086956521739, 0, 0,
0, 0, 2.585858585858586, 0,
0, 0, 0, 1].map {
return Int16(Float([=12=]) * Float(divisor)) // divisor = 256
}
以下代码不会产生与上面 CIFilter 中相同的结果。
private func rgbAdjustmentWithMatrix(image sourceImage: UIImage, rotationMatrix: [Int16]) -> UIImage? {
guard
let cgImage = sourceImage.cgImage,
let sourceImageFormat = vImage_CGImageFormat(cgImage: cgImage),
let rgbDestinationImageFormat = vImage_CGImageFormat(
bitsPerComponent: 8,
bitsPerPixel: 32,
colorSpace: CGColorSpaceCreateDeviceRGB(),
bitmapInfo: CGBitmapInfo(rawValue: CGImageAlphaInfo.first.rawValue),
renderingIntent: .defaultIntent) else {
print("Unable to initialize cgImage or colorSpace.")
return nil
}
guard
let sourceBuffer = try? vImage_Buffer(cgImage: cgImage),
var rgbDestinationBuffer = try? vImage_Buffer(width: Int(sourceBuffer.width),
height: Int(sourceBuffer.height),
bitsPerPixel: rgbDestinationImageFormat.bitsPerPixel) else {
print("Unable to initialize source buffer or destination buffer.")
return nil
}
defer {
sourceBuffer.free()
rgbDestinationBuffer.free()
}
do {
let toRgbConverter = try vImageConverter.make(sourceFormat: sourceImageFormat, destinationFormat: rgbDestinationImageFormat)
try toRgbConverter.convert(source: sourceBuffer, destination: &rgbDestinationBuffer)
} catch {
print("Unable to initialize converter or unable to convert.")
return nil
}
guard var resultBuffer = try? vImage_Buffer(width: Int(sourceBuffer.width),
height: Int(sourceBuffer.height),
bitsPerPixel: rgbDestinationImageFormat.bitsPerPixel) else {
print("Unable to initialize result buffer.")
return nil
}
defer {
resultBuffer.free()
}
var error: vImage_Error
let divisor: Int32 = 256
let preBias = [Int16](repeating: -256, count: 4)
let postBias = [Int32](repeating: 256 * divisor, count: 4)
error = vImageMatrixMultiply_ARGB8888(&rgbDestinationBuffer,
&resultBuffer,
rotationMatrix,
divisor,
preBias,
postBias,
0)
guard error == kvImageNoError else { return nil }
if let cgImage = try? resultBuffer.createCGImage(format: rgbDestinationImageFormat) {
return UIImage(cgImage: cgImage)
} else {
return nil
}
}
可能是颜色 space 的问题？或者 vImageMatrixMultiply_ARGB8888 输入矩阵与 CIFilter 输入矩阵不同？
更新
因此，看起来 vImageMatrixMultiply_ARGB8888 需要以下顺序的值：
let rotationMatrix = [
1, 0, 0, 0, // A
0, 1.9692307692307693, 0, 0, // R
0, 0, 2.226086956521739, 0, // G
0, 0, 0, 2.585858585858586 // B
].map { return Int16([=10=] * Float(divisor)) } // divisor = 0x1000
这与隐含 BGRA 的 Apple 示例代码不一致。可能该矩阵原本打算与不同的 pixelBuffer 格式一起使用 - 或者其他一些问题。
我相信您遇到的另一个问题 运行 是 CIFilter 使用默认的 CIContext。当我 运行 得到一个 linearSRGB workingColorSpace.
let context = CIContext()
print(context.workingColorSpace ?? "")
输出：
<CGColorSpace 0x7fe4abd06d30> (kCGColorSpaceICCBased; kCGColorSpaceModelRGB; sRGB Linear)
因此，您可以将 CGColorSpaceCreateDeviceRGB() 指定为 CIFilter 的 CIContext workingColorSpace，或者在 vImage 用法中将 rgbDestinationImageFormat colorSpace 设置为 .linearSRGB。在这个和更正后的矩阵顺序之间，我相信你的输出图像现在会匹配。
// error handling removed for brevity
let ciImage = CIImage(cgImage: cgImage)
let colorMatrix = CIFilter(name: "CIColorMatrix")!
colorMatrix.setDefaults()
colorMatrix.setValue(ciImage, forKey: "inputImage")
colorMatrix.setValue(CIVector(x: 1.9692307692307693, y: 0, z: 0, w: 0), forKey: "inputRVector")
colorMatrix.setValue(CIVector(x: 0, y: 2.226086956521739, z: 0, w: 0), forKey: "inputGVector")
colorMatrix.setValue(CIVector(x: 0, y: 0, z: 2.585858585858586, w: 0), forKey: "inputBVector")
colorMatrix.setValue(CIVector(x: 0, y: 0, z: 0, w: 1), forKey: "inputAVector")
let context = CIContext(options: [.workingColorSpace : CGColorSpaceCreateDeviceRGB()]) // without this, colorSpace defaults to linearSRGB
return context.createCGImage(colorMatrix.outputImage!, from: rect)!
在这种情况下，可能不需要预先和 post 偏差，除非您有其他原因这样做。
最后，您可能会受益于更大的除数。虽然像素数据是每通道 8 位，但累加器是 32 位，矩阵值是 16 位。大多数参考代码使用 0x1000 (4096) 的除数。
func rgbAdjustmentWithMatrix(image sourceImage: NSImage, rotationMatrix: [Int16]) -> CGImage? {
var rect = CGRect(x: 0, y: 0, width: sourceImage.size.width, height: sourceImage.size.height)
guard
let cgImage = sourceImage.cgImage(forProposedRect: &rect, context: nil, hints: nil),
let sourceImageFormat = vImage_CGImageFormat(cgImage: cgImage),
let rgbDestinationImageFormat = vImage_CGImageFormat(
bitsPerComponent: 8,
bitsPerPixel: 32,
colorSpace: CGColorSpaceCreateDeviceRGB(),
// can match CIFilter default with this:
// colorSpace: CGColorSpace(name: CGColorSpace.linearSRGB)!,
bitmapInfo: CGBitmapInfo(rawValue: CGImageAlphaInfo.first.rawValue),
renderingIntent: .defaultIntent)
else {
print("Unable to initialize cgImage or colorSpace.")
return nil
}
guard
var sourceBuffer = try? vImage_Buffer(cgImage: cgImage),
var rgbDestinationBuffer = try? vImage_Buffer(width: Int(sourceBuffer.width),
height: Int(sourceBuffer.height),
bitsPerPixel: rgbDestinationImageFormat.bitsPerPixel)
else {
fatalError("Error initializing source and destination buffers.")
}
defer {
sourceBuffer.free()
rgbDestinationBuffer.free()
}
do {
let toRgbConverter = try vImageConverter.make(sourceFormat: sourceImageFormat, destinationFormat: rgbDestinationImageFormat)
try toRgbConverter.convert(source: sourceBuffer, destination: &rgbDestinationBuffer)
} catch {
fatalError(error.localizedDescription)
}
let divisor: Int32 = 0x1000 // matrix values are 16 bit and accumulator is 32 bit
// 4096 gives us decent overhead for the matrix operation
// 12-bit color
let preBias: [Int16] = [0, 0, 0, 0] // or simply pass nil
let postBias: [Int32] = [0, 0, 0, 0] // or simply pass nil
let error = vImageMatrixMultiply_ARGB8888(&rgbDestinationBuffer,
&rgbDestinationBuffer,
rotationMatrix,
divisor,
preBias,
postBias,
vImage_Flags(kvImageNoFlags))
if error != kvImageNoError { print("Error: \(error)") }
let result = try? rgbDestinationBuffer.createCGImage(format: rgbDestinationImageFormat)
return result
}
上一个答案
查看您的代码和输出图像，我相信您将红色和蓝色系数颠倒了。如果是这样，您将像这样填充 vImage 矩阵：
rotationMatrix = [2.585858585858586, 0, 0, 0 // b
0, 2.226086956521739, 0, 0, // g
0, 0, 1.9692307692307693, 0, // r
0, 0, 0, 1].map { // a
return Int16(Float([=15=]) * Float(divisor)) // divisor = 256
}
这与 desaturating a selected portion of an image 的 Apple vImage 示例代码一致。
let desaturationMatrix = [
0.0722, 0.0722, 0.0722, 0,
0.7152, 0.7152, 0.7152, 0,
0.2126, 0.2126, 0.2126, 0,
0, 0, 0, 1
].map {
return Int16([=16=] * Float(divisor))
}
请注意，coefficients for Rec709 到 Luma 的转换为：
Y = R * 0.2126 + G * 0.7152 + B * 0.0722