UIImage* image = imgView.image;
CGRect r;
r.origin = CGPointZero;
r.size = image.size;
CGFloat scaleFactor = r.size.width * 1.0 / newImage.size.width;

UIGraphicsBeginImageContext(r.size);

// draw original image into the context
[image drawAtPoint:CGPointZero];

// get the context for CoreGraphics
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextScaleCTM(ctx, scaleFactor, -1.0 * scaleFactor);
CGContextTranslateCTM(ctx, 0, r.size.height);

CGContextBeginTransparencyLayer(ctx, nil);
CGContextSetAlpha(ctx, .25);
CGContextDrawImage(ctx, r, CGImageCreateWithImageInRect(newImage.CGImage, r));
CGContextEndTransparencyLayer(ctx);

// make image out of bitmap context
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

// free the context
UIGraphicsEndImageContext();
[imgView setImage: newImage];