将UIImage转换为CVPixelBufferRef

问题描述

我想将UIImage对象转换为CVPixelBufferRef对象，但我绝对不知道。而我找不到任何示例代码执行此类操作。

I want to convert a UIImage object to a CVPixelBufferRef object, but I have absolutly no idea. And I can't find any example code doing anything like this.

有人可以帮助我吗？ THX提前！

Can someone please help me? THX in advance!

C YA

推荐答案

有不同的方式为此，这些函数从 CGImage 转换像素缓冲区。 UImage 是 CGImage 的包装器，因此要获得CGImage，您只需要调用方法 .CGImage 。

其他方法也是从缓冲区（已发布）创建 CIImage 或使用加速框架，这可能是最快但也最难的。

There are different ways to do that, those functions convert a pixel buffer from a CGImage. UImage is a wrapper around CGImage, thus to get a CGImage you just need to call the method .CGImage.
The other ways are also create a CIImage from the buffer (already posted) or use the Accelerate framework, that is probably the fastest but also the hardest.

- (CVPixelBufferRef) pixelBufferFromCGImage: (CGImageRef) image
{
    NSDictionary *options = @{
                              (NSString*)kCVPixelBufferCGImageCompatibilityKey : @YES,
                              (NSString*)kCVPixelBufferCGBitmapContextCompatibilityKey : @YES,
                              };

    CVPixelBufferRef pxbuffer = NULL;
    CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, CGImageGetWidth(image),
                        CGImageGetHeight(image), kCVPixelFormatType_32ARGB, (__bridge CFDictionaryRef) options,
                        &pxbuffer);
    if (status!=kCVReturnSuccess) {
        NSLog(@"Operation failed");
    }
    NSParameterAssert(status == kCVReturnSuccess && pxbuffer != NULL);

    CVPixelBufferLockBaseAddress(pxbuffer, 0);
    void *pxdata = CVPixelBufferGetBaseAddress(pxbuffer);

    CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef context = CGBitmapContextCreate(pxdata, CGImageGetWidth(image),
                                                 CGImageGetHeight(image), 8, 4*CGImageGetWidth(image), rgbColorSpace,
                                                 kCGImageAlphaNoneSkipFirst);
    NSParameterAssert(context);

    CGContextConcatCTM(context, CGAffineTransformMakeRotation(0));
    CGAffineTransform flipVertical = CGAffineTransformMake( 1, 0, 0, -1, 0, CGImageGetHeight(image) );
    CGContextConcatCTM(context, flipVertical);
    CGAffineTransform flipHorizontal = CGAffineTransformMake( -1.0, 0.0, 0.0, 1.0, CGImageGetWidth(image), 0.0 );
    CGContextConcatCTM(context, flipHorizontal);

    CGContextDrawImage(context, CGRectMake(0, 0, CGImageGetWidth(image),
                                           CGImageGetHeight(image)), image);
    CGColorSpaceRelease(rgbColorSpace);
    CGContextRelease(context);

    CVPixelBufferUnlockBaseAddress(pxbuffer, 0);
    return pxbuffer;
}

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