Reading tiff Image from Oracle long raw by c# not working

Question

I have a long raw column contains a tiff image which is saved by oracle form application, I'm trying to retrieve the image by c# and save it with no luck, the image is valid, but it display crappy drawing.

DataBase column definition

SIGNATURE     NOT NULL LONG RAW()  

C# Code

internal void save(string account) { var commonAccount = new List();

        using (OracleConnection cn = new OracleConnection(ConfigurationManager.ConnectionStrings["-----"].ConnectionString))
        {
            var imgCmd = new OracleCommand("select SIGNATURE, number, code, name  from table_name where number = ***** and code = *****", cn);
            imgCmd.InitialLONGFetchSize = -1;
            cn.Open();

            var reader = imgCmd.ExecuteReader();
            if (reader.Read())
            {
                //var v1 = reader[0];
                var v2 = reader[1].ToString();
                var v3 = reader[2].ToString();
                var v4 = reader[3].ToString();

                OracleBinary imgBinary = reader.GetOracleBinary(0);

                // Get the bytes from the binary obj
                byte[] imgBytes = imgBinary.IsNull ? null : imgBinary.Value;

                var newData = Convert.ToBase64String(imgBytes);


                MemoryStream stream = new MemoryStream();
                stream.Write(imgBytes, 0, imgBytes.Length);
                Bitmap bm = new Bitmap(stream);
                bm.Save("d:\\image.tif", System.Drawing.Imaging.ImageFormat.Tiff);
            }

            reader.Close();
        }

The saved image looks like

I built new oracle form and bound the image with the column, and it displayed correctly, any idea?

EDIT: I found that the image in Oracle database saved as Big-Endian byte order

Answer 1

After few days of understanding and finding solutions around, the following solved my problem, the code below convert to another type of image encoding also do converting to little-endian

Please note that, the code is using BitMiracle.LibTiff library,

        private string GetBase64Data(byte [] image)
    {
        var data = string.Empty;
        using (MemoryStream ms = new MemoryStream(image))
        {
            using (Tiff tif = Tiff.ClientOpen("in-memory", "r", ms, new TiffStream()))
            {
                // Find the width and height of the image
                FieldValue[] value = tif.GetField(TiffTag.IMAGEWIDTH);
                int width = value[0].ToInt();

                value = tif.GetField(TiffTag.IMAGELENGTH);
                int height = value[0].ToInt();

                // Read the image into the memory buffer
                int[] raster = new int[height * width];
                if (!tif.ReadRGBAImage(width, height, raster))
                {
                    return data;
                }

                using (Bitmap bmp = new Bitmap(width, height, PixelFormat.Format24bppRgb))
                {
                    Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height);

                    BitmapData bmpdata = bmp.LockBits(rect, ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
                    byte[] bits = new byte[bmpdata.Stride * bmpdata.Height];

                    for (int y = 0; y < bmp.Height; y++)
                    {
                        int rasterOffset = y * bmp.Width;
                        int bitsOffset = (bmp.Height - y - 1) * bmpdata.Stride;

                        for (int x = 0; x < bmp.Width; x++)
                        {
                            int rgba = raster[rasterOffset++];
                            bits[bitsOffset++] = (byte)((rgba >> 16) & 0xff);
                            bits[bitsOffset++] = (byte)((rgba >> 8) & 0xff);
                            bits[bitsOffset++] = (byte)(rgba & 0xff);
                        }
                    }

                    System.Runtime.InteropServices.Marshal.Copy(bits, 0, bmpdata.Scan0, bits.Length);
                    bmp.UnlockBits(bmpdata);

                    MemoryStream ims = new MemoryStream();
                    bmp.Save(ims, ImageFormat.Bmp);
                    data = Convert.ToBase64String(ims.ToArray());
                }
            }
        }

        return data;
    }