如何将 BGRA 图像保存到 iphone，然后将其带到笔记本电脑上进行后期处理

Posted 2023-05-07

【中文标题】如何将 BGRA 图像保存到 iphone，然后将其带到笔记本电脑上进行后期处理

【英文标题】：How do I save a BGRA image to iphone and then take it to a laptop for post-processing

【发布时间】：2016-04-07 02:37:51

【问题描述】：

我想用iphone的摄像头拍摄原始图像数据，然后在笔记本电脑中使用matlab或opencv对其进行后期处理。所以我需要将这些原始图像数据从 iphone 带到笔记本电脑。

目前，我使用 AVFoudnation 获取 32BGRA 图像（它是原始图像数据，对吗？）。我将它保存为文件，但我无法从 iphone 中获取它。 （有没有不越狱的解决方案？）

以下是一些相关代码：

    if let videoConnection = stillImageOutput!.connectionWithMediaType(AVMediaTypeVideo) 
        videoConnection.videoOrientation = AVCaptureVideoOrientation.Portrait
        stillImageOutput?.captureStillImageAsynchronouslyFromConnection(videoConnection, completionHandler: (sampleBuffer, error) in
            if (sampleBuffer != nil)                                    
                // get the raw image data
                let cameraFrame = CMSampleBufferGetImageBuffer(sampleBuffer)

                CVPixelBufferLockBaseAddress(cameraFrame!, 0)

                let rawImage = CVPixelBufferGetBaseAddress(cameraFrame!)
                let bytesPerRow = CVPixelBufferGetBytesPerRow(cameraFrame!)
                let rawImageData = NSData.init(bytes: rawImage, length: bytesPerRow*CVPixelBufferGetHeight(cameraFrame!))

                // process the rawImageData, we now save it
                var paths = NSSearchPathForDirectoriesInDomains (.DocumentDirectory, .UserDomainMask, true);
                let documentsDirectory = paths[0]
                let fileName = documentsDirectory.stringByAppendingString("/rawImageData")                    

                do 
                    try rawImageData.writeToFile(fileName, options: NSDataWritingOptions.DataWritingFileProtectionComplete)
                 catch 

                
                print("Raw image data write successfully.")
                print("Path of raw image data: ", fileName)                   
                CVPixelBufferUnlockBaseAddress(cameraFrame!, 0)               
            
        )
    

我是否需要将BGRA数据保存到相册然后取出，如果是，我该怎么做（使用UIImage？）

谢谢。

更新：

我将BGRA图像转换为UIImage并使用UIImageWriteToSavedPhotosAlbum将其保存到相册，然后我使用空投将图像文件带到may mac。但是，我发现图像是JPEG格式。怎么了？ 以下是代码：

            if (sampleBuffer != nil)                    
                let rawImage:UIImage = self.imageFromSampleBuffer(sampleBuffer)
                self.capturedImage.image = rawImage
                UIImageWriteToSavedPhotosAlbum(rawImage, nil, nil, nil)                    
                print("Raw Image write to photo album successfully")  
            

// Create a UIImage from sample buffer data
func imageFromSampleBuffer(sampleBuffer : CMSampleBufferRef) -> UIImage

// Get a CMSampleBuffer's Core Video image buffer for the media data
let  imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
// Lock the base address of the pixel buffer
CVPixelBufferLockBaseAddress(imageBuffer!, 0);


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

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

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

// Create a bitmap graphics context with the sample buffer data
var bitmapInfo: UInt32 = CGBitmapInfo.ByteOrder32Big.rawValue
bitmapInfo |= CGImageAlphaInfo.PremultipliedLast.rawValue & CGBitmapInfo.AlphaInfoMask.rawValue
let context = CGBitmapContextCreate(baseAddress, width, height, 8,
bytesPerRow, colorSpace, bitmapInfo);
// Create a Quartz image from the pixel data in the bitmap graphics context
let quartzImage = CGBitmapContextCreateImage(context);
// Unlock the pixel buffer
CVPixelBufferUnlockBaseAddress(imageBuffer!,0);

// Create an image object from the Quartz image
let image = UIImage.init(CGImage: quartzImage!);

return (image);

【问题讨论】：

你想在 MATLAB 中使用什么格式？ MATLAB 不能导入任何类型的图像吗？

Matlab无法导入BGRA图像，我可以将原始数据保存为iphone中的bmp并取出到笔记本电脑吗？

【参考方案1】：

我找到了一个解决方案：将 BGRA 转换为 UIImage，再转换为 PNG，然后将其保存到相册中。由于PNG是一种无损压缩图像格式，这意味着我也得到了bmp图像。

                let rawImage:UIImage = self.imageFromSampleBuffer(sampleBuffer)                    
                let img = UIImagePNGRepresentation(rawImage)
                let pngImg = UIImage.init(data: img!)                                       
                self.capturedImage.image = pngImg
                UIImageWriteToSavedPhotosAlbum(pngImg!, nil, nil, nil)                   
                print("PNG Image write to photo album successfully")