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我使用Apple公司的这个众所周知的示例代码将相机缓存静止图像转换为UIImages。从相机缓冲区iOS中转换图像。使用AVFoundation捕获静止图像
-(UIImage*) getUIImageFromBuffer:(CMSampleBufferRef) imageSampleBuffer{
// Get a CMSampleBuffer's Core Video image buffer for the media data
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(imageSampleBuffer);
if (imageBuffer==NULL) {
NSLog(@"No buffer");
}
// Lock the base address of the pixel buffer
if((CVPixelBufferLockBaseAddress(imageBuffer, 0))==kCVReturnSuccess){
NSLog(@"Buffer locked successfully");
}
void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer);
// Get the number of bytes per row for the pixel buffer
size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
NSLog(@"bytes per row %zu",bytesPerRow);
// Get the pixel buffer width and height
size_t width = CVPixelBufferGetWidth(imageBuffer);
NSLog(@"width %zu",width);
size_t height = CVPixelBufferGetHeight(imageBuffer);
NSLog(@"height %zu",height);
// Create a device-dependent RGB color space
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
// Create a bitmap graphics context with the sample buffer data
CGContextRef context = CGBitmapContextCreate(baseAddress, width, height, 8,
bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
// Create a Quartz image from the pixel data in the bitmap graphics context
CGImageRef quartzImage = CGBitmapContextCreateImage(context);
// Free up the context and color space
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
// Create an image object from the Quartz image
UIImage *image= [UIImage imageWithCGImage:quartzImage scale:SCALE_IMAGE_RATIO orientation:UIImageOrientationRight];
// Release the Quartz image
CGImageRelease(quartzImage);
// Unlock the pixel buffer
CVPixelBufferUnlockBaseAddress(imageBuffer,0);
return (image);}
问题是，通常您获得的图像旋转90°。使用方法+ imageWithCGImage：scale：orientation我可以旋转它，但在进入此方法之前，我正在尝试使用CTM函数旋转和缩放图像，然后将其传递给UIImage。问题在于CTM转换不影响图像。
我在问自己为什么...是因为我锁定了缓冲区？或者是因为上下文是与图像内部一起创建的，所以这些更改只会影响进一步的mod？
谢谢