UIImageJPEGRepresentation giving 2x images on retina display - iphone

Question

I have this code, which creates an image, and then adds some effects to it and sizes it down to make largeThumbnail.
UIImage *originalImage = [UIImage imageWithData:self.originalImage];
thumbnail = createLargeThumbnailFromImage(originalImage);
NSLog(#"thumbnail: %f", thumbnail.size.height);
NSData *thumbnailData = UIImageJPEGRepresentation(thumbnail, 1.0);
Later on:
UIImage *image = [UIImage imageWithData:self.largeThumbnail];
NSLog(#"thumbnail 2: %f", image.size.height);
NSLog returns:
thumbnail: 289.000000
thumbnail 2: 578.000000
As you can see, when it converts the image back from data, it makes it 2x the size. Any ideas why this may be happening?
Large thumbnail code:
UIImage *createLargeThumbnailFromImage(UIImage *image) {
UIImage *resizedImage;
resizedImage = [image imageScaledToFitSize:LARGE_THUMBNAIL_SIZE];
CGRect largeThumbnailRect = CGRectMake(0, 0, resizedImage.size.width, resizedImage.size.height);
UIGraphicsBeginImageContextWithOptions(resizedImage.size, NO, 0);
CGContextRef context = UIGraphicsGetCurrentContext();
//Image
CGContextTranslateCTM(context, 0, resizedImage.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextDrawImage(context, largeThumbnailRect, resizedImage.CGImage);
//Border
CGContextSaveGState(context);
CGRect innerRect = rectForRectWithInset(largeThumbnailRect, 1.5);
CGMutablePathRef borderPath = createRoundedRectForRect(innerRect, 0);
CGContextSetStrokeColorWithColor(context, [[UIColor whiteColor] CGColor]);
CGContextSetLineWidth(context, 3);
CGContextAddPath(context, borderPath);
CGContextStrokePath(context);
CGContextRestoreGState(context);
UIImage *thumbnail = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return thumbnail;
}

Answer 1

Try replacing the part where you load the second image:
UIImage *image = [UIImage imageWithData:self.largeThumbnail];
with this one:
UIImage *jpegImage = [UIImage imageWithData:self.largeThumbnail];
UIImage *image = [UIImage imageWithCGImage:jpegImage.CGImage scale:originalImage.scale orientation:jpegImage.imageOrientation];
What happens here is that the image scale is not set, so you get double image dimensions.