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    <p>The reason your code doesn't work is because the imageOrientation on the code that you have is not being taken into account. Specifically, if the imageOrientation is right/left, then you need to both rotate the image and swap width/height. Here is some code to do this:</p> <pre><code>-(UIImage*)imageByScalingToSize:(CGSize)targetSize { UIImage* sourceImage = self; CGFloat targetWidth = targetSize.width; CGFloat targetHeight = targetSize.height; CGImageRef imageRef = [sourceImage CGImage]; CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef); CGColorSpaceRef colorSpaceInfo = CGImageGetColorSpace(imageRef); if (bitmapInfo == kCGImageAlphaNone) { bitmapInfo = kCGImageAlphaNoneSkipLast; } CGContextRef bitmap; if (sourceImage.imageOrientation == UIImageOrientationUp || sourceImage.imageOrientation == UIImageOrientationDown) { bitmap = CGBitmapContextCreate(NULL, targetWidth, targetHeight, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo); } else { bitmap = CGBitmapContextCreate(NULL, targetHeight, targetWidth, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo); } if (sourceImage.imageOrientation == UIImageOrientationLeft) { CGContextRotateCTM (bitmap, radians(90)); CGContextTranslateCTM (bitmap, 0, -targetHeight); } else if (sourceImage.imageOrientation == UIImageOrientationRight) { CGContextRotateCTM (bitmap, radians(-90)); CGContextTranslateCTM (bitmap, -targetWidth, 0); } else if (sourceImage.imageOrientation == UIImageOrientationUp) { // NOTHING } else if (sourceImage.imageOrientation == UIImageOrientationDown) { CGContextTranslateCTM (bitmap, targetWidth, targetHeight); CGContextRotateCTM (bitmap, radians(-180.)); } CGContextDrawImage(bitmap, CGRectMake(0, 0, targetWidth, targetHeight), imageRef); CGImageRef ref = CGBitmapContextCreateImage(bitmap); UIImage* newImage = [UIImage imageWithCGImage:ref]; CGContextRelease(bitmap); CGImageRelease(ref); return newImage; } </code></pre> <p>This will resize your image and rotate it to the correct orientation. If you need the definition for radians, it is:</p> <pre><code>static inline double radians (double degrees) {return degrees * M_PI/180;} </code></pre> <p>The answer Daniel gave is also correct, but it suffers from the problem that it is not thread-safe, since you're using UIGraphicsBeginImageContext(). Since the above code only uses CG functions, you're all set. I also have a similar function to resize and do proper aspect fill on images - let me know if that's what you're looking for.</p> <p>Note: I got the original function from <a href="http://www.iphonedevsdk.com/forum/iphone-sdk-development/7307-resizing-photo-new-uiimage.html" rel="noreferrer">this post</a>, and did some modifications to make it work on JPEGs.</p>
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