Trying to convert byte[] to jpg file

Question

I have a web api service that accepts an image (byte[]) as part of the data for the post/create method. I save the image data in a sql server blob column. When I use the corresponding get method I see the data as

"ffd8ffe000104a46494600010100000100010000ffdb004300100b0c0e0c0a100e0d0e..." (shortened)

When I look at the bytes of the original image they look just like that (snip from my binary editor):

![Manual Method[(http://sdrv.ms/1bjgsnX)

I need a way to convert my data into the correct jpg file. I’ve tried several things but finally had to manually do it. I didn't include here my attempts at using Image but they were also many and unsuccessful. There must be a more standard way of doing what I need to do. For all of these methods I use the same File writing code:

string base64String = Convert.ToBase64String(photoFromDB, Base64FormattingOptions.None);
//various methods to convert that to a byte[] tempBytes
string DestFilePath = "testManual.jpg";
System.IO.FileStream fs = new System.IO.FileStream(DestFilePath,
System.IO.FileMode.Create, System.IO.FileAccess.Write);
fs.Write(tempBytes, 0, tempBytes.Length);
fs.Close();

Here are my attempts and the outcomes:

![All Methods[(http://sdrv.ms/1bjgegH)

//Manual method that works but I don’t like.
byte[] tempBytes = new byte[base64String.Length/2];
string tempString;
byte tempByte;
int count = 0;

for (int i = 0; i < base64String.Length; i = i+2)
{
    tempString = base64String.Substring(i, 2);
    tempByte = Convert.ToByte(tempString, 16);
    tempBytes[count++] = tempByte;
}

//Unicode convert
//I can see my data here but it has extra nulls included.

tempBytes = System.Text.Encoding.Unicode.GetBytes(base64String);



//UTF32 convert
//again can see my data but even more nulls included

tempBytes = System.Text.Encoding.UTF32.GetBytes(base64String);


//UTF7, UTF8, and Default, ASCII, BigEndianUnicodegive me the same output
//I can see my data but it isn’t correct yet

tempBytes = System.Text.Encoding.UTF7.GetBytes(base64String);
tempBytes = System.Text.Encoding.UTF8.GetBytes(base64String);
tempBytes = System.Text.Encoding.Default.GetBytes(base64String);
tempBytes = System.Text.Encoding.ASCII.GetBytes(base64String);
tempBytes = System.Text.Encoding.BigEndianUnicodegive.GetBytes(base64String);

What’s the secret sauce I’m missing?

Answer 1

I'm not quite sure why you're trying to base64-encode/decode anything here... If you already have a byte array, why not use File.WriteAllBytes(...); to put them into the JPEG file?

Answer 2

For my use, I wrote two small functions for realise this conversion

 #region public byte[] BitmapToBytes(Image bmp, ImageFormat p_Format)
        public byte[] BitmapToBytes(Image bmp, ImageFormat p_Format)
        {
            MemoryStream stream = new MemoryStream();
            try
            {
                bmp.Save(stream, p_Format);
            }
            catch (Exception ex)
            {
            }
            return stream.ToArray();
        }
        #endregion

        #region public Image BytesToBitmap(byte[] bytes)
        public Image BytesToBitmap(byte[] bytes)
        {
            MemoryStream stream = null;
            try
            {
                stream = new MemoryStream(bytes);
            }
            catch (Exception ex)
            {
            }

            return new Bitmap(stream);
        }
        #endregion

Answer 3

Thorsten Dittmar is right.

1. You have data in byte[]

2. Then you make conversion TO Base64 string

   string base64String = Convert.ToBase64String(photoFromDB, Base64FormattingOptions.None); //various methods to convert that to a byte[] tempBytes ....

3. Then you do some conversion from string (Base64String) back to array[]!

   ... tempByte = Convert.ToByte(tempString, 16); ...

   Why? Just try File.WriteAllBytes(...) as Thorsten Dittmar suggested.