Following WWDC 2023 "Support HDR images in your app", I'm trying to save 48-megapixel ProRAWs (taken on an iPhone 14 Pro Max) as HDR HEICs to the Photo Library. After processing the ProRAW file using CIRAWFilter, whether I use CIContext.heif10Representation() or convert to a CGImage, then UIImage, and use UIImage.heicData(), I get photos that behave oddly in the Photo Library. They appear too dark, and visibly brighten when first viewed, but more problematic is that the photos brighten a great deal more when you edit them with the Photos editor. This is the behavior when using the itur_2100_PQ color space, but itur_2100_HLG behaves similarly, except that it gets dramatically darker when edited. This behavior occurs whether CIRAWFilter.extendedDynamicRangeAmount is set to 0.0, or 2.0, or not set at all. So what am I doing wrong? Here is a minimal iOS app -- well, just the ContentView -- that demonstrates the issue. You also need a .dng ProRAW file included in the project directory named test.dng. I'd love to include such a file, but I can't. Be prepared for a multi-second wait when you save the photo. import SwiftUI import Photos struct ContentView: View { let context = CIContext() let hdrColorSpace = CGColorSpace(name: CGColorSpace.itur_2100_PQ)! var body: some View { VStack(spacing: 100) { Button("Save Photo From CGImage/UIImage") { savePhotoFromUIImage() } Button("Save Photo From CIImage") { savePhotoDirectFromCIImage() } }.padding(60) } //convert RAW with CIRAWFilter to CIImage, then convert to CGImage, then UIImage, then HEIF private func savePhotoFromUIImage() { if let ciImage = processRAW(url: Bundle.main.url(forResource:"test", withExtension: "dng")!) { guard let outputCGImage = context.createCGImage(ciImage, from: ciImage.extent, format: .RGB10, colorSpace: hdrColorSpace) else { return } let uiImage = UIImage(cgImage: outputCGImage) if let heicData = uiImage.heicData() { saveHEIFPhotoToLibrary(imageData: heicData) } else { print("Failed to convert UIImage to HEIC") } } } //convert RAW with CIRAWFilter to CIImage, then to HEIF private func savePhotoDirectFromCIImage() { if let ciImage = processRAW(url: Bundle.main.url(forResource:"test", withExtension: "dng")!) { do { let heif = try context.heif10Representation(of: ciImage, colorSpace: hdrColorSpace) saveHEIFPhotoToLibrary(imageData: heif) } catch { print("Failed to get HEIF representation from CIContext") } } } private func processRAW(url: URL) -> CIImage? { guard let coreRawFilter = CIRAWFilter(imageURL: url) else { return nil } coreRawFilter.extendedDynamicRangeAmount = 2.0 //the issue persists whether this is not set, or set to 0, or set to, say, 2.0 guard let ciImage = coreRawFilter.outputImage else { return nil } return ciImage } private func saveHEIFPhotoToLibrary(imageData: Data) { PHPhotoLibrary.shared().performChanges({ let creationRequest = PHAssetCreationRequest.forAsset() let options = PHAssetResourceCreationOptions() creationRequest.addResource(with: .photo, data: imageData, options: options) }) { success, error in if let error = error { print("Error saving photo: \(error.localizedDescription)") } else { print("Photo saved.") } } } }