iPhone BitmapImageRep

I have a buffer which has JPEG image data. I need to display this image in UIImageView. I need to convert this image buffer into an object of UIImage and use it as follows

NSData *data = [NSData dataWithContentsOfFile:appFile]; UIImage *theImage = [[UIImage alloc] initWithData:data];

I get the image displayed but with a low resolution as compared to the actual resolution. Do I need to convert it into a Bitmap first and then use it with UIImage? I don't seem to be able to use NSBitmapImageRep. Any ideas on how can this be achieved?

From stackoverflow

• If the UIImageView frame dimensions are different than the source image dimensions, you'll get a resized version of the image. The quality can be pretty rough depending on how much of a conversion is being performed.

  I found this code on the net somewhere (sorry original author - I've lost the attribution) that performs a smoother resize:

  UIImage* resizedImage(UIImage *inImage, CGRect thumbRect)
  {
      CGImageRef   imageRef = [inImage CGImage];
      CGImageAlphaInfo alphaInfo = CGImageGetAlphaInfo(imageRef);
  
      // There's a wierdness with kCGImageAlphaNone and CGBitmapContextCreate
      // see Supported Pixel Formats in the Quartz 2D Programming Guide
      // Creating a Bitmap Graphics Context section
      // only RGB 8 bit images with alpha of kCGImageAlphaNoneSkipFirst, kCGImageAlphaNoneSkipLast, kCGImageAlphaPremultipliedFirst,
      // and kCGImageAlphaPremultipliedLast, with a few other oddball image kinds are supported
      // The images on input here are likely to be png or jpeg files
      if (alphaInfo == kCGImageAlphaNone)
       alphaInfo = kCGImageAlphaNoneSkipLast;
  
      // Build a bitmap context that's the size of the thumbRect
      CGContextRef bitmap = CGBitmapContextCreate(
                 NULL,
                 thumbRect.size.width,  // width
                 thumbRect.size.height,  // height
                 CGImageGetBitsPerComponent(imageRef), // really needs to always be 8
                 4 * thumbRect.size.width, // rowbytes
                 CGImageGetColorSpace(imageRef),
                 alphaInfo
                 );
  
      // Draw into the context, this scales the image
      CGContextDrawImage(bitmap, thumbRect, imageRef);
  
      // Get an image from the context and a UIImage
      CGImageRef ref = CGBitmapContextCreateImage(bitmap);
      UIImage* result = [UIImage imageWithCGImage:ref];
  
      CGContextRelease(bitmap); // ok if NULL
      CGImageRelease(ref);
  
      return result;
  }