A FileDialog.Filter generator for all supported images

Recently, I had to write a quick app to load images into a database, and wanted to restrict the file type to just images. You can do this with the OpenFileDialog.Filter property, but it is a pain working out what file extensions to permit. This method returns a Filter compatible string built from the image formats the current system understands.

        /// <summary>
        /// Get the Filter string for all supported image types.
        /// This can be used directly to the FileDialog class Filter Property.
        /// </summary>
        /// <returns></returns>
        public string GetImageFilter()
            {
            StringBuilder allImageExtensions = new StringBuilder();
            string separator = "";
            ImageCodecInfo[] codecs = ImageCodecInfo.GetImageEncoders();
            Dictionary<string, string> images = new Dictionary<string, string>();
            foreach (ImageCodecInfo codec in codecs)
                {
                allImageExtensions.Append(separator);
                allImageExtensions.Append(codec.FilenameExtension);
                separator = ";";
                images.Add(string.Format("{0} Files: ({1})", codec.FormatDescription, codec.FilenameExtension),
                           codec.FilenameExtension);
                }
            StringBuilder sb = new StringBuilder();
            if (allImageExtensions.Length > 0)
                {
                sb.AppendFormat("{0}|{1}", "All Images", allImageExtensions.ToString());
                }
            images.Add("All Files", "*.*");
            foreach (KeyValuePair<string, string> image in images)
                {
                sb.AppendFormat("|{0}|{1}", image.Key, image.Value);
                }
            return sb.ToString();
            }

This returns a string that (on my system) is:

All Images|*.BMP;*.DIB;*.RLE;*.JPG;*.JPEG;*.JPE;*.JFIF;*.GIF;*.TIF;*.TIFF;*.PNG|
BMP Files: (*.BMP;*.DIB;*.RLE)|*.BMP;*.DIB;*.RLE|
JPEG Files: (*.JPG;*.JPEG;*.JPE;*.JFIF)|*.JPG;*.JPEG;*.JPE;*.JFIF|
GIF Files: (*.GIF)|*.GIF|
TIFF Files: (*.TIF;*.TIFF)|*.TIF;*.TIFF|
PNG Files: (*.PNG)|*.PNG|
All Files|*.*

Suitable for loading directly into the OpenFileDialog or SaveFileDialog Filter property. [edit]Typos, and abstract trucated by the system. Abstract shorted, and added to main text body - OriginalGriff[/edit]