Iphone 使图像黑白相间？

我还有一个quartz 2d（iphone）问题：

如何将ImageView的所有颜色更改为黑色和白色，而只保留红色

DD

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这是我在其他论坛上发现的东西，它似乎很有效

+1对你来说，这很有效，甚至我用了这段代码…谢谢你，伙计

UIImage *originalImage = [info objectForKey:UIImagePickerControllerOriginalImage];  this image we get from UIImagePickerController

    CGColorSpaceRef colorSapce = CGColorSpaceCreateDeviceGray();
    CGContextRef context = CGBitmapContextCreate(nil, originalImage.size.width, originalImage.size.height, 8, originalImage.size.width, colorSapce, kCGImageAlphaNone);
    CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
    CGContextSetShouldAntialias(context, NO);
    CGContextDrawImage(context, CGRectMake(0, 0, originalImage.size.width, originalImage.size.height), [originalImage CGImage]);

    CGImageRef bwImage = CGBitmapContextCreateImage(context);
    CGContextRelease(context);
    CGColorSpaceRelease(colorSapce);

    UIImage *resultImage = [UIImage imageWithCGImage:bwImage]; // This is result B/W image.
    CGImageRelease(bwImage);