convert binary to bitmap using memory stream

Question

Hi I wanna convert binary array to bitmap and show image in a picturebox. I wrote the following code but I got exception that says that the parameter is not valid .

  public static Bitmap ByteToImage(byte[] blob)
    {
        MemoryStream mStream = new MemoryStream();
        byte[] pData = blob;
        mStream.Write(pData, 0, Convert.ToInt32(pData.Length));
        Bitmap bm = new Bitmap(mStream);
        mStream.Dispose();
        return bm;

    }

Why are you copying the byte array? Why not just do `using (MemoryStream mStream = new MemoryStream(blob);) {return new Bitmap(mStream);}` — Steven Doggart, Dec 17 '12 at 11:37
You want to convert image to stream and store to database as varbinary? — Dev, Dec 17 '12 at 11:38
this may help you http://satindersinght.blogspot.in/2012/03/save-and-retrive-binarydata-from.html — Satinder singh, Dec 17 '12 at 11:44

Thorsten Dittmar · Accepted Answer · 2013-10-23T17:25:26.870

20

It really depends on what is in blob. Is it a valid bitmap format (like PNG, BMP, GIF, etc?). If it is raw byte information about the pixels in the bitmap, you can not do it like that.

It may help to rewind the stream to the beginning using mStream.Seek(0, SeekOrigin.Begin) before the line Bitmap bm = new Bitmap(mStream);.

public static Bitmap ByteToImage(byte[] blob)
{
    using (MemoryStream mStream = new MemoryStream())
    {
         mStream.Write(blob, 0, blob.Length);
         mStream.Seek(0, SeekOrigin.Begin);

         Bitmap bm = new Bitmap(mStream);
         return bm;
    }
}

edited Oct 23 '13 at 17:25

answered Dec 17 '12 at 11:39

Thorsten Dittmar

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Please take a look at [this rejected edit](http://stackoverflow.com/review/suggested-edits/3181577). From the [msdn](http://msdn.microsoft.com/en-us/library/system.io.memorystream.seek.aspx) it looks like he is right. – gunr2171 Oct 21 '13 at 16:02
How can this work when the MS doc is clearly stating "You must keep the stream open for the lifetime of the Bitmap."? Source: https://learn.microsoft.com/en-us/dotnet/api/system.drawing.bitmap.-ctor?view=netframework-4.6.2#System_Drawing_Bitmap__ctor_System_IO_Stream_ Also, this answer does not work in my case, where I use the Image for Telerik Report. Here I get a rendering error when I dispose the stream. – this.myself Sep 15 '21 at 15:15

score 5 · Answer 2 · answered Dec 17 '12 at 11:38

5

Don't dispose of the MemoryStream. It now belongs to the image object and will be disposed when you dispose the image.

Also consider doing it like this

var ms = new MemoryStream(blob);
var img = Image.FromStream(ms);
.....
img.Dispose(); //once you are done with the image.

answered Dec 17 '12 at 11:38

juharr

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i trace my code i get argumanexeptioninvalid at this code Bitmap bm = new Bitmap(mStream); – heavy Dec 17 '12 at 11:41
2

This is not true! The stream and the byte information do not "belong to the image object". The stream *must* even be disposed of to not get memory leaks. – Thorsten Dittmar Dec 17 '12 at 11:42
@ThorstenDittmar I've worked with this a lot and I can tell you that disposing the memory stream will cause problems. Don't believe me? Try it for yourself. – juharr Dec 17 '12 at 11:43
We're not talking WPF where ;-) – Thorsten Dittmar Dec 17 '12 at 11:45
@ThorstenDittmar Check this out http://social.msdn.microsoft.com/Forums/en/csharpgeneral/thread/5884995d-23ac-4fd9-bae3-878b0da70f76 – juharr Dec 17 '12 at 11:47
2

Well, I tried disposing the stream after loading the image from it. It works fine. – Thorsten Dittmar Dec 17 '12 at 11:57
I'm always disposing MemoryStream and after this I'm using Bitmap. It works fine. – Kostadin Feb 27 '15 at 12:02

score 0 · Answer 3 · answered Dec 17 '12 at 11:46

0

System.IO.MemoryStream mStrm = new System.IO.MemoryStream(your byte array);
Image im = Image.FromStream(mStrm);
im.Save("image.bmp");

Try this. If you still get any error or exception; please post your bytes which you are trying to convert to image. There should be problem in your image stream....

answered Dec 17 '12 at 11:46

Uthistran Selvaraj

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i do it too but i get parameter is not valid exception – heavy Dec 17 '12 at 11:51
Ok friend, can you please post your bytes converted into string here? – Uthistran Selvaraj Dec 17 '12 at 11:55
How do the image bytes get into the database? Are you *really* sure that the bytes in the database represent an image in format PNG, GIF, BMP, etc.? If not, you can not use the `Bitmap` constructor. – Thorsten Dittmar Dec 17 '12 at 11:59

convert binary to bitmap using memory stream

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