title: UIImageJPEGRepresentation giving 2x images on retina display
body: <p>I have this code, which creates an image, and then adds some effects to it and sizes it down to make <code>largeThumbnail</code>.</p>
  
  <pre><code>UIImage *originalImage = [UIImage imageWithData:self.originalImage];
  thumbnail = createLargeThumbnailFromImage(originalImage);
  
  NSLog(@"thumbnail: %f", thumbnail.size.height);
  NSData *thumbnailData = UIImageJPEGRepresentation(thumbnail, 1.0);
  </code></pre>
  
  <p>Later on:</p>
  
  <pre><code>UIImage *image = [UIImage imageWithData:self.largeThumbnail];
  NSLog(@"thumbnail 2: %f", image.size.height);
  </code></pre>
  
  <p>NSLog returns:</p>
  
  <pre><code>thumbnail: 289.000000
  thumbnail 2: 578.000000
  </code></pre>
  
  <p>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?</p>
  
  <p>Large thumbnail code:</p>
  
  <pre><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;
  }
  </code></pre>