Need some help converting cvpixelbuffer data to a jpeg/png in iOS

Question

So I'm trying to get a jpeg/png representation of the grayscale depth maps that are typically used in iOS image depth examples. The depth data is stored in each jpeg as aux data. I've followed some tutorials and I have no problem rendering this gray scale data to the screen, but I can find no way to actually save it as a jpeg/png representation. I'm pretty much using this code: https://www.raywenderlich.com/168312/image-depth-maps-tutorial-ios-getting-started

The depth data is put into a cvpixelbuffer and manipulated accordingly. I believe it's in the format kCVPixelFormatType_DisparityFloat32 .

While I'm able to see this data represented accordingly on the screen, I'm unable to use UIImagePNGRepresentation or UIImageJPGRepresentation . Sure, I could manually capture a screenshot, but that's not really ideal.

I have a suspicion that the cvpixelbuffer data format is not compatible with these UIImage functions and that's why I can't get them to spit out an image.

Does anyone have any suggestions?

Answer 1

// CVPixelBuffer to UIImage
let ciImageDepth            = CIImage(cvPixelBuffer: cvPixelBufferDepth)
let contextDepth:CIContext  = CIContext.init(options: nil)
let cgImageDepth:CGImage    = contextDepth.createCGImage(ciImageDepth, from: ciImageDepth.extent)!
let uiImageDepth:UIImage    = UIImage(cgImage: cgImageDepth, scale: 1, orientation: UIImage.Orientation.up)

// Save UIImage to Photos Album
UIImageWriteToSavedPhotosAlbum(uiImageDepth, nil, nil, nil)

Answer 2

I figured it out. I had to convert to a CGImage first. Ended up doing cvPixelBuffer to CIImage to CGImage to UIImage.

Answer 3

Posting a swift code sample in case anyone wants to use it.

let ciimage = CIImage(cvPixelBuffer: depthBuffer) // depth cvPixelBuffer
let depthUIImage = UIImage(ciImage: ciimage)