Under Sonoma 14.4 the compression option doesn't work with PNG images. It works for JPG/HEIF. Preview can export PNG file to HEIC with compression option. What am I missing? Previously this has worked. I am trying with 0.01 and 0.9 as compression quality and the file size is the same for PNG.
Is Preview using some trick to convert the image using ciContext.createCGImage?
PS: Compression option of 1.0 was broken under 14.4 RC and Preview created empty file.
func heifImageDataUsingDestination(at url: URL, compressionQuality : CGFloat) -> Data? {
guard let imageSource = CGImageSourceCreateWithURL(url as CFURL, nil) else { return nil }
guard let cgImage = CGImageSourceCreateImageAtIndex(imageSource, 0, nil) else { return nil }
var mutableData = NSMutableData()
guard let imageDestination = CGImageDestinationCreateWithData(mutableData, "public.heic" as CFString, 1, nil) else { return nil }
let options = [ kCGImageDestinationLossyCompressionQuality: compressionQuality ] as CFDictionary
CGImageDestinationAddImage(imageDestination, cgImage, options)
let success = CGImageDestinationFinalize(imageDestination)
if success {
return mutableData as Data
}
return nil
}
func heifImageDataUsingCIContext(at url: URL, compressionQuality : CGFloat) -> Data? {
guard let ciImage = CIImage(contentsOf: url) else { return nil }
let context = CIContext()
let colorspace = ciImage.colorSpace ?? CGColorSpaceCreateDeviceRGB()
let options = [CIImageRepresentationOption(rawValue: kCGImageDestinationLossyCompressionQuality as String) : compressionQuality]
return context.heifRepresentation(of: ciImage, format: .RGBA8, colorSpace: colorspace, options: options)
}
