//the following is appropriate call to do this if img is the UIImage instance.
//img=[img scaleProportionalToSize:CGSizeMake(320, 480)];

@interface UIImage (UIImageFunctions)
	- (UIImage *) scaleToSize: (CGSize)size;
	- (UIImage *) scaleProportionalToSize: (CGSize)size;
@end
@implementation UIImage (UIImageFunctions)

- (UIImage *) scaleToSize: (CGSize)size
{
	// Scalling selected image to targeted size
	CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
	CGContextRef context = CGBitmapContextCreate(NULL, size.width, size.height, 8, 0, colorSpace, kCGImageAlphaPremultipliedLast);
	CGContextClearRect(context, CGRectMake(0, 0, size.width, size.height));

	if(self.imageOrientation == UIImageOrientationRight)
	{
		CGContextRotateCTM(context, -M_PI_2);
		CGContextTranslateCTM(context, -size.height, 0.0f);
		CGContextDrawImage(context, CGRectMake(0, 0, size.height, size.width), self.CGImage);
	}
	else
		CGContextDrawImage(context, CGRectMake(0, 0, size.width, size.height), self.CGImage);

	CGImageRef scaledImage=CGBitmapContextCreateImage(context);

	CGColorSpaceRelease(colorSpace);
	CGContextRelease(context);

	UIImage *image = [UIImage imageWithCGImage: scaledImage];

	CGImageRelease(scaledImage);

	return image;
}

- (UIImage *) scaleProportionalToSize: (CGSize)size1
{
	if(self.size.width>self.size.height)
	{
		NSLog(@"LandScape");
		size1=CGSizeMake((self.size.width/self.size.height)*size1.height,size1.height);
	}
	else
	{
		NSLog(@"Potrait");
		size1=CGSizeMake(size1.width,(self.size.height/self.size.width)*size1.width);
	}

	return [self scaleToSize:size1];
}

@end