Rotate CGImage taken from video frame

Question

This is Apple's code (from Technical Q&A QA1702) for getting a UIImage from a video buffer. Unfortunately, the image returned is rotated 90 degrees. How do I edit this so that the image returned is correctly oriented?

- (UIImage *) imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer 
{
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer); 
    CVPixelBufferLockBaseAddress(imageBuffer, 0); 

    void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer); 

    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer); 
    size_t width = CVPixelBufferGetWidth(imageBuffer); 
    size_t height = CVPixelBufferGetHeight(imageBuffer); 

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); 

    CGContextRef context = CGBitmapContextCreate(baseAddress, width, height, 8, 
                                                 bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst); 

    CGImageRef quartzImage = CGBitmapContextCreateImage(context); 
    CVPixelBufferUnlockBaseAddress(imageBuffer,0);

    CGContextRelease(context); 
    CGColorSpaceRelease(colorSpace);

    UIImage *image = [UIImage imageWithCGImage:quartzImage];

    CGImageRelease(quartzImage);

    return (image);
}

score 26 · Accepted Answer · edited Mar 11 '11 at 13:30

26

Depends on whether you are using the front camera or the back camera

int frontCameraImageOrientation = UIImageOrientationLeftMirrored;
int backCameraImageOrientation = UIImageOrientationRight;

UIImage *image = [[UIImage alloc] initWithCGImage:newImage scale:(CGFloat)1.0 orientation:frontCameraImageOrientation];

edited Mar 11 '11 at 13:30

Valerii Hiora

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answered Dec 04 '10 at 20:54

John Carter

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Thanks! That worked great - with the slight correction of including the orientation: parameter label in the method call. – Drew C Dec 04 '10 at 22:37
1

Awesome! and so simple, specially after a long fight with CG with no successful results, tks! – Felipe Sabino Jul 18 '12 at 01:08
1

The image is still roated 90 degree anticlockwise – Sumit Kumar Saha May 12 '17 at 10:58
Awesome! Searching for exactly this hint. – Chanchal Warde Sep 01 '17 at 10:14

score 3 · Answer 2 · answered Apr 02 '15 at 18:45

3

You can change videoOrientation, this way you get a correct image

connection.videoOrientation = AVCaptureVideoOrientationPortrait

Because by default Video orientation is not portrait.

answered Apr 02 '15 at 18:45

mohamede1945

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score 1 · Answer 3 · answered Apr 15 '15 at 08:35

Just rotate the context

Simply rotate the context in radians. This call would rotate the context 90 degrees.

CGFloat degrees = 90.f;
CGFloat radians = degrees * (M_PI / 180.f);
CGContextRotateCTM(context, radians);

You can easily set this method to take the desired orientation and rotate accordingly.

Rotate CGImage taken from video frame

3 Answers3

Just rotate the context

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