Image resizer

ImageResizer.cs

        /// <summary>
        /// Resizes the image for compression
        /// </summary>
        /// <param name="img"></param>
        /// <param name="maxWidth"></param>
        /// <param name="maxHeight"></param>
        /// <returns></returns>
        private static Image ResizeImage(Image img, int maxWidth, int maxHeight) {
            if (img.Height < maxHeight && img.Width < maxWidth) return img;
            using (img) {
                Double xRatio = (double)img.Width / maxWidth;
                Double yRatio = (double)img.Height / maxHeight;
                Double ratio = Math.Max(xRatio, yRatio);
                int nnx = (int)Math.Floor(img.Width / ratio);
                int nny = (int)Math.Floor(img.Height / ratio);
                Bitmap cpy = new Bitmap(nnx, nny, PixelFormat.Format32bppArgb);
                using (Graphics gr = Graphics.FromImage(cpy)) {
                    gr.Clear(Color.Transparent);
 
                    // This is said to give best quality when resizing images
                    gr.InterpolationMode = InterpolationMode.HighQualityBicubic;
 
                    gr.DrawImage(img,
                        new Rectangle(0, 0, nnx, nny),
                        new Rectangle(0, 0, img.Width, img.Height),
                        GraphicsUnit.Pixel);
                }
                return cpy;
            }
        }