Ios 将UIImage转换为8灰度型像素缓冲区

我可以将

UIImage

转换为ARGB

CVPixelBuffer

，但现在我正在尝试将

UIImage

转换为灰度单缓冲区。 我原以为代码已经通过了，但coreML模型抱怨说：

“Error Domain=com.apple.CoreML Code=1”映像不是预期的类型 8-灰色，不受支持（40）”

这是我到目前为止得到的灰度

CGContext

：

public func pixelBufferGray(width: Int, height: Int) -> CVPixelBuffer? {

        var pixelBuffer : CVPixelBuffer?
        let attributes = [kCVPixelBufferCGImageCompatibilityKey: kCFBooleanTrue, kCVPixelBufferCGBitmapContextCompatibilityKey: kCFBooleanTrue]

        let status = CVPixelBufferCreate(kCFAllocatorDefault, Int(width), Int(height), kCVPixelFormatType_8IndexedGray_WhiteIsZero, attributes as CFDictionary, &pixelBuffer)

        guard status == kCVReturnSuccess, let imageBuffer = pixelBuffer else {
            return nil
        }

        CVPixelBufferLockBaseAddress(imageBuffer, CVPixelBufferLockFlags(rawValue: 0))

        let imageData =  CVPixelBufferGetBaseAddress(imageBuffer)

        guard let context = CGContext(data: imageData, width: Int(width), height:Int(height),
                                      bitsPerComponent: 8, bytesPerRow: CVPixelBufferGetBytesPerRow(imageBuffer),
                                      space: CGColorSpaceCreateDeviceGray(),
                                      bitmapInfo: CGImageAlphaInfo.none.rawValue) else {
                                        return nil
        }

        context.translateBy(x: 0, y: CGFloat(height))
        context.scaleBy(x: 1, y: -1)

        UIGraphicsPushContext(context)
        self.draw(in: CGRect(x:0, y:0, width: width, height: height) )
        UIGraphicsPopContext()
        CVPixelBufferUnlockBaseAddress(imageBuffer, CVPixelBufferLockFlags(rawValue: 0))

        return imageBuffer

    }

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任何帮助都将不胜感激

即使图像被称为灰度，正确的像素格式是：

kCVPixelFormatType\u OneComponent8

---

希望这段完整的代码片段能够帮助其他人：

public func pixelBufferGray(width: Int, height: Int) -> CVPixelBuffer? {

        var pixelBuffer : CVPixelBuffer?
        let attributes = [kCVPixelBufferCGImageCompatibilityKey: kCFBooleanTrue, kCVPixelBufferCGBitmapContextCompatibilityKey: kCFBooleanTrue]

        let status = CVPixelBufferCreate(kCFAllocatorDefault, Int(width), Int(height), kCVPixelFormatType_OneComponent8, attributes as CFDictionary, &pixelBuffer)

        guard status == kCVReturnSuccess, let imageBuffer = pixelBuffer else {
            return nil
        }

        CVPixelBufferLockBaseAddress(imageBuffer, CVPixelBufferLockFlags(rawValue: 0))

        let imageData =  CVPixelBufferGetBaseAddress(imageBuffer)

        guard let context = CGContext(data: imageData, width: Int(width), height:Int(height),
                                      bitsPerComponent: 8, bytesPerRow: CVPixelBufferGetBytesPerRow(imageBuffer),
                                      space: CGColorSpaceCreateDeviceGray(),
                                      bitmapInfo: CGImageAlphaInfo.none.rawValue) else {
                                        return nil
        }

        context.translateBy(x: 0, y: CGFloat(height))
        context.scaleBy(x: 1, y: -1)

        UIGraphicsPushContext(context)
        self.draw(in: CGRect(x:0, y:0, width: width, height: height) )
        UIGraphicsPopContext()
        CVPixelBufferUnlockBaseAddress(imageBuffer, CVPixelBufferLockFlags(rawValue: 0))

        return imageBuffer

    }

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在这段代码中创建上下文时，是否尝试用kCVPixelFormatType_8IndexedGray_WhiteIsZero或kCVPixelFormatType_8IndexedGray_索引替换空格参数？感谢您的帮助，正确的像素格式是kCVPixelFormatType_OneComponent8，对于灰度UIImage8，您可以投票支持我的评论，至少loli刚才这么做了，干杯！很高兴您得到了它正在工作…但您不需要自己进行像素缓冲区转换来将图像提供给核心ML模型：Vision framework会为您这样做。请看，我不明白如何使用此代码段，上下文从何处获取图像信息？这是UIImage扩展吗？请提供一个示例。谢谢