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Extracting HDR Gain Map from iOS 14.1+ (iPhone 12+) photos
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| import UIKit | |
| import MobileCoreServices.UTCoreTypes | |
| if #available(iOS 14.1, *) { | |
| let input = Bundle.main.url(forResource: "IMG_0037", withExtension: "HEIC")! | |
| let output = FileManager().temporaryDirectory.appendingPathComponent("IMG_0037.GAIN_MAP.BMP") | |
| let source = CGImageSourceCreateWithURL(input as CFURL, nil)! | |
| // urn:com:apple:photo:2020:aux:hdrgainmap | |
| let dataInfo = CGImageSourceCopyAuxiliaryDataInfoAtIndex(source, 0, kCGImageAuxiliaryDataTypeHDRGainMap)! as Dictionary | |
| let data = dataInfo[kCGImageAuxiliaryDataInfoData] as! Data | |
| let description = dataInfo[kCGImageAuxiliaryDataInfoDataDescription]! as! [String: Int] | |
| let size = CGSize(width: description["Width"]!, height: description["Height"]!) | |
| let ciImage = CIImage(bitmapData: data, bytesPerRow: description["BytesPerRow"]!, size: size, format: .L8, colorSpace: nil) | |
| let cgImage = CIContext().createCGImage(ciImage, from: CGRect(origin: CGPoint(x: 0, y: 0), size: size))! | |
| let destRef = CGImageDestinationCreateWithURL(output as CFURL, kUTTypeBMP, 1, nil)! | |
| CGImageDestinationAddImage(destRef, cgImage, [:] as CFDictionary) | |
| CGImageDestinationFinalize(destRef) | |
| print(output) | |
| } |
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Some more information from the apple's developer site: https://developer.apple.com/videos/play/wwdc2024/10177/