问题描述
我正在尝试生成 HEIF 输出文件,但这样做时会出现奇怪的对角线。其他输出格式都没有表现出这些奇怪的线条。见下图。问题似乎是裁剪,但错误仅显示在 HEIF 输出文件中。
我可以使用以下 Playground 代码复制此代码,您可以从此处下载 https://duncangroenewald.com/files/SampleApps/CoreImageHEIFExporterBug-2.zip
我有一个关于 Apple 的错误报告,他们提到了“子像素错误”——我不知道那是什么或者为什么这些只会用 heif 输出格式表现出来或者如何防止它们——任何想法或者只是这样做看起来像是 Apple 代码中的错误?
编辑。需要明确的是,这不是操场问题,因为问题发生在 macOS 应用程序中。
我怀疑这在生成 HEIF 输出时一定是一个 CIContext
错误,因为它只与 heif 输出文件一起显示。但是,我对亚像素错误一无所知,也不知道为什么 Apple 认为它们应该与此问题相关。也许有更多 Core Image 知识的人可以提出一些可能的解决方案。
import Cocoa
let files = ["/Users/duncangroenewald/Development/Playgrounds/CoreImageHEIFExporterBug/DSC02022.ARW","/Users/duncangroenewald/Development/Playgrounds/CoreImageHEIFExporterBug/DSC02018.ARW"
]
let destFilePath = "/Users/duncangroenewald/Development/Playgrounds/CoreImageHEIFExporterBug"
let destUrl = URL(fileURLWithPath: destFilePath)
let exporter = Exporter()
var crops = [CGRect(x: 0,y: 0,width: 5310,height: 3212),CGRect(x: 0,width: 5311,width: 5312,width: 5313,height: 3212)]
for file in files {
exporter.processRAWFile(file,destPath: destFilePath,crops: crops)
}
print("Done!")
import AppKit
import CoreImage
import CoreImage.CIFilterBuiltins
import oslog
public class Exporter {
var formats: [String] = ["heif","png"]
// Get the CIContext
let ciContext = CIContext()
var imageOrientation: Int = 0
var imageNativeSize: CGSize = .zero
var crops: [CGRect] = [.zero]
public init() {
}
public func processRAWFile(_ path: String,destPath: String,crops: [CGRect]) {
print("processRAWFile XXX")
self.crops = crops
let url = URL(fileURLWithPath: path)
let filename = url.deletingPathExtension().lastPathComponent
let destDirUrl = URL(fileURLWithPath: destPath)
print("destDirUrl: \(destDirUrl)")
for crop in crops {
let cropName = "\(filename)_\(crop.width)x\(crop.height)_\(useDefaultRAW ? "default" : "")"
for format in formats {
let destUrl = destDirUrl.appendingPathComponent(cropName).appendingPathExtension(format)
print("destFile: \(destUrl)")
self.exportFile(url: url,destUrl: destUrl,crop: crop,format: format)
}
}
}
func exportFile(url: URL,destUrl: URL,crop: CGRect,format: String){
print("exportFile \(url)")
print("destFile: \(destUrl)")
guard let rawFilter = CIFilter(imageURL: url,options: nil),let outputimage = rawFilter.outputimage else {
print("Failed to load \(url.lastPathComponent) for exporting")
return
}
let processImage = self.crop(outputimage,rect: crop)
let options = [kCGImageDestinationLossyCompressionQuality as CIImageRepresentationoption: 1.0 as CGFloat]
let colorSpace = CGColorSpace(name: CGColorSpace.sRGB)!
let imgFormat = CIFormat.RGBA16
do {
switch format {
case "tiff":
try ciContext.writeTIFFRepresentation(of: processImage,to: destUrl,format: imgFormat,colorSpace: colorSpace,options: options)
case "jpeg":
try ciContext.writeJPEGRepresentation(of: processImage,options: options)
case "png":
try ciContext.writePNGRepresentation(of: processImage,options: options)
case "heif":
try ciContext.writeHEIFRepresentation(of: processImage,options: options)
default:
try ciContext.writePNGRepresentation(of: processImage,options: options)
}
} catch {
print("Error exporting \(format): \(error.localizedDescription)")
}
}
var useDefaultRAW: Bool = true
func crop(_ ciImage: CIImage,rect: CGRect)->CIImage {
if let cropped = self.cropFilter(ciImage,rect: rect) {
return cropped
} else {
print("Error cropping image !")
return ciImage
}
}
func cropFilter(_ input: CIImage,rect: CGRect) -> CIImage? {
// Getting a dashed border !!
guard let cropFilter = CIFilter(name: "CICrop") else {
print("Error no CICrop filter found !")
return input
}
let ciVect = CIVector(cgRect: rect)
cropFilter.setValue(input,forKey: kCIInputimageKey)
cropFilter.setValue(ciVect,forKey: "inputRectangle")
return cropFilter.value(forKey: kCIoUtputimageKey) as? CIImage
}
}
解决方法
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