Swift 3 Color Space macOS不是IOS

debugcn 发表于 Dev

用户名

如何将RGB图像转换为其灰度颜色空间？我可以找到很多针对iOS的代码，但找不到针对macOS的代码。而且Apple的文档都以客观的C ....

    let width = image.size.width
    let height = image.size.height
    let imageRect = NSMakeRect(0, 0, width, height);
    let colorSpace = CGColorSpaceCreateDeviceGray();


    let bits = image.representations.first as! NSBitmapImageRep;
    bitmap!.representationUsingType(NSBitmapImageFileType.NSPNGFileType, properties: nil)


    let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.none.rawValue);
    let context = CGContext(data: nil, width: Int(width), height: Int(height), bitsPerComponent: 8, bytesPerRow: 0, space: colorSpace, bitmapInfo: bitmapInfo.rawValue);
    context.draw(image.cgImage!, in : imageRect);// and this line is wrong obviously..

这就是我到目前为止所得到的..只是从互联网上复制和粘贴..但是我不知道如何进一步...

用户名

我找到了一种有趣的方式来执行此操作。.我的代码只是从下面的三个来源中复制而来。

如何从nsimage快速创建灰度图像？

使用COCOA和NSImage的灰度图像

更改NSImage的色彩空间：第二个答复

我的代码：

func saveImage(image:NSImage, destination:URL) throws{
    let rep = greyScale(image);
    var data = rep.representation(using: NSJPEGFileType, properties: [:]);
    try data?.write(to: destination);

}

// rgb2gray
func greyScale(image: NSImage) -> NSBitmapImageRep{
    let w = image.size.width
    let h = image.size.height
    let imageRect : NSRect! = NSMakeRect(0,0, w, h);
    let colourSpace : ColourSpace! = CGColorSpaceCreateDeviceGray();
    let context : CGContext! = CGContext(data: nil, width: Int(w), 
                                        height: Int(h), bitsPerComponent: 8, 
                                        bytesPerRow: 0, space: colorSpace, 
                                        bitmapInfo: CGImageAlphaInfo.none.rawValue);        

    context.draw(nsImageToCGImage(image: image), in: imageRect);
    let greyImage : CGImage! = context.makeImage();

    return NSBitmapImageRep(cgImage: greyImage);
}


func nsImageToCGImage(image: NSImage) -> CGImage{
    if let imageData = image.tiffRepresentation as NSData! {
        let imageSource : CGImageSource! = CGImageSourceCreateWithData(imageData, 
                                        nil);
        let image = CGImageSourceCreateImageAtIndex(imageSource, 0, nil);
        return image;
    }
    return nil;
}

我仍在尝试了解其背后的原理。

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