OpenCV Mat与UIImage之间的转换

　　UIImage 转 OpenCV cvMat：

- (cv::Mat)cvMatWithImage:(UIImage *)image
{
    CGColorSpaceRef colorSpace = CGImageGetColorSpace(image.CGImage);
    CGFloat cols = image.size.width;
    CGFloat rows = image.size.height;
    
    cv::Mat cvMat(rows, cols, CV_8UC4); // 8 bits per component, 4 channels
    
    CGContextRef contextRef = CGBitmapContextCreate(cvMat.data,                 // Pointer to backing data
                                                    cols,                       // Width of bitmap
                                                    rows,                       // Height of bitmap
                                                    8,                          // Bits per component
                                                    cvMat.step[0],              // Bytes per row
                                                    colorSpace,                 // Colorspace
                                                    kCGImageAlphaNoneSkipLast |
                                                    kCGBitmapByteOrderDefault); // Bitmap info flags
    
    CGContextDrawImage(contextRef, CGRectMake(0, 0, cols, rows), image.CGImage);
    CGContextRelease(contextRef);
    
    return cvMat;
}

　　OpenCV cvMat 转 UIImage ：　

24 - (UIImage *)UIImageFromCVMat:(cv::Mat)cvMat {
25     NSData *data = [NSData dataWithBytes:cvMat.data length:cvMat.elemSize()*cvMat.total()];
26     
27     CGColorSpaceRef colorSpace;
28     CGBitmapInfo bitmapInfo;
29     
30     if (cvMat.elemSize() == 1) {
31         colorSpace = CGColorSpaceCreateDeviceGray();
32         bitmapInfo = kCGImageAlphaNone | kCGBitmapByteOrderDefault;
33     } else {
34         colorSpace = CGColorSpaceCreateDeviceRGB();
35         bitmapInfo = kCGBitmapByteOrder32Little | (
36                                                    cvMat.elemSize() == 3? kCGImageAlphaNone : kCGImageAlphaNoneSkipFirst
37                                                    );
38     }
39     
40     CGDataProviderRef provider = CGDataProviderCreateWithCFData((__bridge CFDataRef)data);
41     
42     // Creating CGImage from cv::Mat
43     CGImageRef imageRef = CGImageCreate(
44                                         cvMat.cols,                 //width
45                                         cvMat.rows,                 //height
46                                         8,                          //bits per component
47                                         8 * cvMat.elemSize(),       //bits per pixel
48                                         cvMat.step[0],              //bytesPerRow
49                                         colorSpace,                 //colorspace
50                                         bitmapInfo,                 // bitmap info
51                                         provider,                   //CGDataProviderRef
52                                         NULL,                       //decode
53                                         false,                      //should interpolate
54                                         kCGRenderingIntentDefault   //intent
55                                         );
56     
57     // Getting UIImage from CGImage
58     UIImage *finalImage = [UIImage imageWithCGImage:imageRef];
59     CGImageRelease(imageRef);
60     CGDataProviderRelease(provider);
61     CGColorSpaceRelease(colorSpace);
62     
63     return finalImage;
64 }