iphone - 将图像设为黑白？

Question

我还有另一个 quartz 2d (iphone) 问题:

如何将 ImageView 的所有颜色更改为黑白并仅保留红色？？？

DD

Answer 1

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);

这是我在其他论坛上找到的东西，它似乎有效!!!