从Mat(OpenCV)转换到UIImage后出现黑色背景

Question

我有一个应用程序，使用OpenCV库的一些功能来编辑图像。在将UIImage转换为Mat和Mat转换为UIImage之后，我在图像中得到一个黑色背景请告诉我如何修理它

我用来将UIImage转换为Mat的代码

- (cv::Mat)cvMatFromUIImage:(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 (color channels + alpha)
CGContextRef contextRef = CGBitmapContextCreate(cvMat.data,                 // Pointer to  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;

}

我用来将Mat转换为UIImage的代码

-(UIImage *)UIImageFromCVMat:(cv::Mat)cvMat
{
NSData *data = [NSData dataWithBytes:cvMat.data length:cvMat.elemSize()*cvMat.total()];
CGColorSpaceRef colorSpace;
if (cvMat.elemSize() == 1) {
colorSpace = CGColorSpaceCreateDeviceGray();
} else {
colorSpace = CGColorSpaceCreateDeviceRGB();
}
CGDataProviderRef provider = CGDataProviderCreateWithCFData((__bridge CFDataRef)data);
// Creating CGImage from cv::Mat
CGImageRef imageRef = CGImageCreate(cvMat.cols,                                 //width
cvMat.rows,                                 //height
8,                                          //bits per component
8 * cvMat.elemSize(),                       //bits per pixel
cvMat.step[0],                            //bytesPerRow
colorSpace,                                 //colorspace
kCGImageAlphaNone|kCGBitmapByteOrderDefault,// bitmap info
provider,                                   //CGDataProviderRef
NULL,                                       //decode
false,                                      //should interpolate
kCGRenderingIntentDefault                   //intent
);

// Getting UIImage from CGImage
UIImage *finalImage = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
CGDataProviderRelease(provider);
CGColorSpaceRelease(colorSpace);
return finalImage;

}

代码示例

-(UIImage *)stroked:(UIImage *)image color:(int)color strock:(float)strock {
cv::Mat img = [self cvMatFromUIImage:image];
return [self UIImageFromCVMat:img];

}

Answer 1

功能正常，无复制问题。由于提示，我将kCGImageAlphaNoneSkipLast|kCGBitmapByteOrderDefault调整为kCGBitmapByteOrder32Big | kCGImageAlphaPremultipliedLast

kCGImageAlphaNone | kCGBitmapByteOrderDefaultkCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedLast