How do I convert a png picture to jpg format?

//Make sure this is in your using block
using System.Drawing;
using System.Drawing.Imaging;

private bool ChangeToJPG(string file)
{
    try
    {
        //In case you're fussy about PNGs
        if (!file.ToLower().EndsWith(".png"))
           throw new NotImplementedException("Not a png file");
        if (!System.IO.File.Exists(file))
           throw new NotImplementedException("File not found");

        Image png = Image.FromFile(file);
        png.Save(file.Replace(".png", ".jpg").Replace(".PNG", ".JPG"), ImageFormat.Jpeg);
        return true;
    }
    catch
    {
        return false;
    }
}