有什么方法可以更改 NSimage 或 NSBitmapImageRep/CGimage 等的颜色空间。我对任何方式都持开放态度。最好是 photoshop 的处理方式。
最佳答案
你在下面看到的代码有问题
CGImageRef CGImageCreateCopyWithColorSpace (
CGImageRef image,
CGColorSpaceRef colorspace
);
不起作用,因为 Quartz2D 不支持 CMYK 图像或灰度图像的 alpha,它仅受 RGB 图像支持。 你应该做的是创建 2 个图像,然后在 CMYK 颜色空间和带 alpha 的图像的情况下组合。我搜索了很多关于这个主题的内容,终于找到了。可能是这个问题的作者不再需要它,但其他人可能需要它。
新建
NSBitmapImageRep
let imageRep = NSBitmapImageRep(bitmapDataPlanes: nil, pixelsWide: Int(round(imageSize.width)), pixelsHigh: Int(round(imageSize.height)), bitsPerSample: 8, samplesPerPixel: 4, hasAlpha: false, isPlanar: false, colorSpaceName: NSDeviceCMYKColorSpace, bitmapFormat: NSBitmapFormat(rawValue: 0), bytesPerRow: Int(round(imageSize.width) * CGFloat(4)), bitsPerPixel: 0)
您需要将图像绘制到新位图中 假设你有
colorSpace: NSColorSpace
let context = NSGraphicsContext(bitmapImageRep: imageRep) NSGraphicsContext.saveGraphicsState() NSGraphicsContext.setCurrentContext(context) imageRep.setProperty(NSImageColorSyncProfileData, withValue: colorSpace.ICCProfileData) // Do your drawing here NSGraphicsContext.restoreGraphicsState()
在此之后,您将拥有一个 imageRep,它是具有正确色彩空间但没有 alpha(透明度)的图像。
你需要一个 mask 位图。获取掩码很棘手。
let imageRep = NSBitmapImageRep(bitmapDataPlanes: nil, pixelsWide: Int(round(imageSize.width)), pixelsHigh: Int(round(imageSize.height)), bitsPerSample: 8, samplesPerPixel: 1, hasAlpha: false, isPlanar: false, colorSpaceName: NSDeviceWhiteColorSpace, bitmapFormat: NSBitmapFormat(rawValue: 0), bytesPerRow: Int(round(imageSize.width)), bitsPerPixel: 0)
用透明度将白色图像剪辑到您的图像
if let graphicsPort = NSGraphicsContext.currentContext()?.graphicsPort { let context = unsafeBitCast(graphicsPort, CGContextRef.self) let imgRect = NSRect(origin: NSPoint.zero, size: image.extent.size) let ciContext = CIContext() let cgImage = ciContext.createCGImage(image, fromRect: image.extent) CGContextClipToMask(context, imgRect, cgImage) }
将所有像素着色为白色,这将被剪裁成图像。
let context = NSGraphicsContext(bitmapImageRep: imageRep) NSGraphicsContext.saveGraphicsState() NSGraphicsContext.setCurrentContext(context) imageRep.setProperty(NSImageColorSyncProfileData, withValue: colorSpace.ICCProfileData) NSColor.whiteColor().setFill() NSBezierPath.fillRect(NSRect(origin: NSPoint.zero, size: imageSize)) NSGraphicsContext.restoreGraphicsState()
在这一步中,您有一个图像和一个 mask 。接下来我们需要将它们组合起来。我正在使用这个小算法(您需要验证掩码和源图像具有相同的大小和相同的 colorSpaceModel):
func createCMYKAImageRepByApplingAlphaMask(srcImageRep: NSBitmapImageRep, alphaMaskImageRep alphaMask: NSBitmapImageRep) -> NSBitmapImageRep? { if canApplyMaskRepOnImageRep(srcImageRep, maskRep: alphaMask) == false { return nil } let alphaData = alphaMask.bitmapData let srcData = srcImageRep.bitmapData if let imageWithAlphaMaskRep = createEmptyCMYKABitmapImageRep(alphaMask.size) { if let colorSpaceData = imageColorSpace?.ICCProfileData { imageWithAlphaMaskRep.setProperty(NSImageColorSyncProfileData, withValue: colorSpaceData) } fillPixelsWithComponentsData(imageWithAlphaMaskRep, components: { (pixelIdx: Int) -> (UInt8, UInt8, UInt8, UInt8, UInt8) in let cyan = srcData[pixelIdx * 4 + 0] let magenta = srcData[pixelIdx * 4 + 1] let yellow = srcData[pixelIdx * 4 + 2] let black = srcData[pixelIdx * 4 + 3] let alpha = alphaData[pixelIdx] return (cyan, magenta, yellow, black, alpha) }) return imageWithAlphaMaskRep } return nil } func createEmptyBitmapImageRep() -> NSBitmapImageRep? { let imageRep = NSBitmapImageRep(bitmapDataPlanes: nil, pixelsWide: Int(round(imageSize.width)), pixelsHigh: Int(round(imageSize.height)), bitsPerSample: 8, samplesPerPixel: 5, hasAlpha: true, isPlanar: false, colorSpaceName: NSDeviceCMYKColorSpace, bitmapFormat: NSBitmapFormat(rawValue: 0), bytesPerRow: Int(round(imageSize.width) * CGFloat(5)), bitsPerPixel: 0) return imageRep } private func fillPixelsWithComponentsData(imgRep: NSBitmapImageRep, components: (Int) -> (cyan:UInt8, magenta:UInt8, yellow:UInt8, black:UInt8, alpha:UInt8)) { let imageRawData = imgRep.bitmapData let imageWidth = Int(imgRep.size.width) let imageHeight = Int(imgRep.size.height) for pixelIdx in 0 ..< (imageWidth * imageHeight) { let (cyan, magenta, yellow, black, alpha) = components(pixelIdx) let fAlpha = Float(alpha) / 255 imageRawData[pixelIdx * 5 + 0] = UInt8(Float(cyan) * fAlpha) imageRawData[pixelIdx * 5 + 1] = UInt8(Float(magenta) * fAlpha) imageRawData[pixelIdx * 5 + 2] = UInt8(Float(yellow) * fAlpha) imageRawData[pixelIdx * 5 + 3] = UInt8(Float(black) * fAlpha) imageRawData[pixelIdx * 5 + 4] = alpha } }
关于objective-c - 改变 NSImage 的颜色空间,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/3253521/