Question

I have a byte array of jp2, how can I convert that to JPG file? Thank you

Thank all the answers. I made some differences and nearly succeeded. Here is how I do it:

using (var reader = command.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        String id = (String)reader["ID"];
                        blob = (byte[])reader["Data"];

                        using (MemoryStream ms = new MemoryStream(blob))
                        {
                            FIBITMAP dib = FreeImage.LoadFromStream(ms);                            
                            if (dib.IsNull)
                            {
                                continue;
                            }                           
                            string jpgName = getJpgName(id);
                            FreeImage.Save(FREE_IMAGE_FORMAT.FIF_JPEG, dib, jpgName, FREE_IMAGE_SAVE_FLAGS.JPEG_QUALITYNORMAL);
                        }
                    }
                }

I read byte[] from database. Now another problem arises; there exists memory leak! Could someone pick it out?

Answer 1

We don’t have anything built in .Net to do this but, You can use FreeImage which is a free library that can do this.

Here is an Example on doing this.

FIBITMAP dib = FreeImage.LoadEx("test.jp2");
//save the image out to disk    
FreeImage.Save(FREE_IMAGE_FORMAT.FIF_JPEG, dib, "test.jpg", FREE_IMAGE_SAVE_FLAGS.JPEG_QUALITYNORMAL);
//or even turn it into a normal Bitmap for later use
Bitmap bitmap = FreeImage.GetBitmap(dib);

For converting from a stream of bytes u can try this:

byte[] myByte = new byte[10];
MemoryStream theMemStream = new MemoryStream();
theMemStream.Write(myByte, 0, myByte.Length);
FreeImageBitmap fbm = FreeImageBitmap.FromStream(theMemStream);
fbm.Save("text.jpg",FREE_IMAGE_STREAM.FIF_JPEG);