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copied!<p>Here's a nicely commented Image Manipulation helper class that you can look at and use. I wrote it as an example of how to perform certain image manipulation tasks in C#. You'll be interested in the <strong>ResizeImage</strong> function that takes a System.Drawing.Image, the width and the height as the arguments.</p> <pre><code>using System; using System.Collections.Generic; using System.Drawing; using System.Drawing.Imaging; namespace DoctaJonez.Drawing.Imaging { /// <summary> /// Provides various image untilities, such as high quality resizing and the ability to save a JPEG. /// </summary> public static class ImageUtilities { /// <summary> /// A quick lookup for getting image encoders /// </summary> private static Dictionary<string, ImageCodecInfo> encoders = null; /// <summary> /// A lock to prevent concurrency issues loading the encoders. /// </summary> private static object encodersLock = new object(); /// <summary> /// A quick lookup for getting image encoders /// </summary> public static Dictionary<string, ImageCodecInfo> Encoders { //get accessor that creates the dictionary on demand get { //if the quick lookup isn't initialised, initialise it if (encoders == null) { //protect against concurrency issues lock (encodersLock) { //check again, we might not have been the first person to acquire the lock (see the double checked lock pattern) if (encoders == null) { encoders = new Dictionary<string, ImageCodecInfo>(); //get all the codecs foreach (ImageCodecInfo codec in ImageCodecInfo.GetImageEncoders()) { //add each codec to the quick lookup encoders.Add(codec.MimeType.ToLower(), codec); } } } } //return the lookup return encoders; } } /// <summary> /// Resize the image to the specified width and height. /// </summary> /// <param name="image">The image to resize.</param> /// <param name="width">The width to resize to.</param> /// <param name="height">The height to resize to.</param> /// <returns>The resized image.</returns> public static System.Drawing.Bitmap ResizeImage(System.Drawing.Image image, int width, int height) { //a holder for the result Bitmap result = new Bitmap(width, height); //set the resolutions the same to avoid cropping due to resolution differences result.SetResolution(image.HorizontalResolution, image.VerticalResolution); //use a graphics object to draw the resized image into the bitmap using (Graphics graphics = Graphics.FromImage(result)) { //set the resize quality modes to high quality graphics.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality; graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; //draw the image into the target bitmap graphics.DrawImage(image, 0, 0, result.Width, result.Height); } //return the resulting bitmap return result; } /// <summary> /// Saves an image as a jpeg image, with the given quality /// </summary> /// <param name="path">Path to which the image would be saved.</param> /// <param name="quality">An integer from 0 to 100, with 100 being the /// highest quality</param> /// <exception cref="ArgumentOutOfRangeException"> /// An invalid value was entered for image quality. /// </exception> public static void SaveJpeg(string path, Image image, int quality) { //ensure the quality is within the correct range if ((quality < 0) || (quality > 100)) { //create the error message string error = string.Format("Jpeg image quality must be between 0 and 100, with 100 being the highest quality. A value of {0} was specified.", quality); //throw a helpful exception throw new ArgumentOutOfRangeException(error); } //create an encoder parameter for the image quality EncoderParameter qualityParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality); //get the jpeg codec ImageCodecInfo jpegCodec = GetEncoderInfo("image/jpeg"); //create a collection of all parameters that we will pass to the encoder EncoderParameters encoderParams = new EncoderParameters(1); //set the quality parameter for the codec encoderParams.Param[0] = qualityParam; //save the image using the codec and the parameters image.Save(path, jpegCodec, encoderParams); } /// <summary> /// Returns the image codec with the given mime type /// </summary> public static ImageCodecInfo GetEncoderInfo(string mimeType) { //do a case insensitive search for the mime type string lookupKey = mimeType.ToLower(); //the codec to return, default to null ImageCodecInfo foundCodec = null; //if we have the encoder, get it to return if (Encoders.ContainsKey(lookupKey)) { //pull the codec from the lookup foundCodec = Encoders[lookupKey]; } return foundCodec; } } } </code></pre> <hr> <h1>Update</h1> <p>A few people have been asking in the comments for samples of how to consume the ImageUtilities class, so here you go.</p> <pre><code>//resize the image to the specified height and width using (var resized = ImageUtilities.ResizeImage(image, 50, 100)) { //save the resized image as a jpeg with a quality of 90 ImageUtilities.SaveJpeg(@"C:\myimage.jpeg", resized, 90); } </code></pre> <h2>Note</h2> <p>Remember that images are disposable, so you need to assign the result of your resize to a using declaration (or you could use a try finally and make sure you call dispose in your finally).</p>

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