迅速-将UIImage转换为纯黑白并检测DataMatrix

Question

我真的需要帮助。我正在创建一个DataMatrix阅读器，部分代码仅具有白色背景，并且会导致AVFoundation出现任何问题，但是另一部分具有灰色且具有微弱的背景（请参见下图），这使我发疯。

我尝试过的事情：

1）AVFoundation及其metaDataOutput仅在白色背景下才能完美使用，而使用闪烁灰色没有成功

2）zxing-实际上找不到swift的任何有效示例，并且他们在GitHub的示例中也没有找到灰色的Datamatrix（以datamatrix作为qr代码类型），将非常感谢这样的教程或其他内容（zxingObjC用于斯威夫特）

3）大约有20个来自cocoapods / github的库-不再是灰色的了

4）然后我发现Vision可以完美地从照片中检测出白色的Datamatrix，因此我决定使用此库并更改了方式：不再捕获视频输出，仅捕获UIImage，然后使用Vision框架处理它们并检测DataMatrix

要转换颜色，我尝试过：

CIFilters（ColorsControls，NoirEffect），GPU过滤器（单色，亮度，averageLuminance，adaptiveTreshold）与参数一起播放

最后，我没有解决方案可以使用DataMatrix贴纸在10到10之间工作。有时它可以与GPUImageAverageLuminanceThresholdFilter和GPUImageAdaptiveThresholdFilter一起使用，但运气约为20％。

我认为，只有在日光下，这20％的运气会随着微光闪烁。

任何建议对我都会有所帮助！ Zxing for Swift可能有一个不错的解决方案，我找不到。还是不需要使用Vision并从AVFoundation获取帧，但是如何？

I-nigma等可以从实时视频中完美捕捉我的贴纸，所以应该有办法。我的扫描仪的Android版本使用Zxing，我想Zxing可以完成这项工作。

我的扫描方案：

fileprivate func createSession(input:AVCaptureDeviceInput) -> Bool {
        let session = AVCaptureSession()        
        if session.canAddInput(input) {
            session.addInput(input)
        } else {
            return false
        }        
        let output = AVCaptureVideoDataOutput()
        if session.canAddOutput(output) {
            output.setSampleBufferDelegate(self, queue: DispatchQueue(label: "com.output"))
            output.videoSettings = [String(kCVPixelBufferPixelFormatTypeKey):kCVPixelFormatType_32BGRA]
            output.alwaysDiscardsLateVideoFrames = true            
            session.addOutput(output)
        }
        self.videoSession = session
        return true
    }

extension ViewController: AVCaptureVideoDataOutputSampleBufferDelegate {
    func convert(cmage:CIImage) -> UIImage
    {
        let context:CIContext = CIContext.init(options: nil)
        let cgImage:CGImage = context.createCGImage(cmage, from: cmage.extent)!
        let image:UIImage = UIImage.init(cgImage: cgImage)
        return image
    }

    func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {

        let threshold:Double = 1.0 / 3
        let timeStamp = CMSampleBufferGetPresentationTimeStamp(sampleBuffer)
        currentTime = Double(timeStamp.value) / Double(timeStamp.timescale)
        if (currentTime - lastTime > threshold) {

            if let image = imageFromSampleBuffer(sampleBuffer: sampleBuffer),
                let cgImage = image.cgImage {

                let ciImage = CIImage(cgImage: cgImage)
//                with CIFilter
//                let blackAndWhiteImage = ciImage.applyingFilter("CIColorControls", parameters: [kCIInputContrastKey: 2.5,
//                                                                                                kCIInputSaturationKey: 0,
//                                                                                                kCIInputBrightnessKey: 0.5]) 
//                let imageToScan = convert(cmage: blackAndWhiteImage) //UIImage(ciImage: blackAndWhiteImage)
//                resImage = imageToScan
//                scanBarcode(cgImage: imageToScan.cgImage!)


                let filter = GPUImageAverageLuminanceThresholdFilter()
                filter.thresholdMultiplier = 0.7
                let imageToScan = filter.image(byFilteringImage: image)
                resImage = imageToScan!
                scanBarcode(cgImage: imageToScan!.cgImage!)
            }
        }
    }

    fileprivate func imageFromSampleBuffer(sampleBuffer : CMSampleBuffer) -> UIImage? {
        guard let imgBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else {
            return nil
        }
        // Lock the base address of the pixel buffer
        CVPixelBufferLockBaseAddress(imgBuffer, CVPixelBufferLockFlags.readOnly)

        // Get the number of bytes per row for the pixel buffer
        let baseAddress = CVPixelBufferGetBaseAddress(imgBuffer)

        // Get the number of bytes per row for the pixel buffer
        let bytesPerRow = CVPixelBufferGetBytesPerRow(imgBuffer)
        // Get the pixel buffer width and height
        let width = CVPixelBufferGetWidth(imgBuffer)
        let height = CVPixelBufferGetHeight(imgBuffer)

        // Create a device-dependent RGB color space
        let colorSpace = CGColorSpaceCreateDeviceRGB()

        // Create a bitmap graphics context with the sample buffer data
        var bitmapInfo: UInt32 = CGBitmapInfo.byteOrder32Little.rawValue
        bitmapInfo |= CGImageAlphaInfo.premultipliedFirst.rawValue & CGBitmapInfo.alphaInfoMask.rawValue
        //let bitmapInfo: UInt32 = CGBitmapInfo.alphaInfoMask.rawValue
        let context = CGContext.init(data: baseAddress, width: width, height: height, bitsPerComponent: 8, bytesPerRow: bytesPerRow, space: colorSpace, bitmapInfo: bitmapInfo)
        // Create a Quartz image from the pixel data in the bitmap graphics context
        let quartzImage = context?.makeImage()
        // Unlock the pixel buffer
        CVPixelBufferUnlockBaseAddress(imgBuffer, CVPixelBufferLockFlags.readOnly)

        CVPixelBufferLockBaseAddress(imgBuffer, .readOnly)

        if var image = quartzImage {
            if shouldInvert, let inverted = invertImage(image) {
                image = inverted
            }
            let output = UIImage(cgImage: image)
            return output
        }
        return nil
    }


    fileprivate func scanBarcode(cgImage: CGImage) {
        let barcodeRequest = VNDetectBarcodesRequest(completionHandler: { request, _ in
            self.parseResults(results: request.results)
        })
        let handler = VNImageRequestHandler(cgImage: cgImage, options: [.properties : ""])
        guard let _ = try? handler.perform([barcodeRequest]) else {
            return print("Could not scan")
        }
    }

    fileprivate func parseResults(results: [Any]?) {
        guard let results = results else {
            return print("No results")
        }
        print("GOT results - ", results.count)
        for result in results {
            if let barcode = result as? VNBarcodeObservation {
                if let code = barcode.payloadStringValue {
                    DispatchQueue.main.async {
                        self.videoSession?.stopRunning()
                        self.resultLabel.text = code
                        self.blackWhiteImageView.image = self.resImage //just to check from what image code scanned
                    }
                } else {
                    print("No results 2")
                }
            } else {
                print("No results 1")
            }
        }
    }
}