Image variable to byte[] array

Question

I'm faced in a problem which i think is simple to solve, just i did something wrong, so: I have an Android tablet, where the user can draw signature, i get the image (.JPEG) by adb.

    ProcessStartInfo adb_copy = new ProcessStartInfo("C:/SCR/adb/adb.exe");
    adb_copy.Arguments = "pull \"mnt/sdcard/sign.jpg\" \"C:\\SCR\\temp\\sign.jpg\"";
    adb_copy.WindowStyle = ProcessWindowStyle.Hidden;
    Process.Start(adb_copy);

I have two Image variables:

Image WORKER_sign;
Image EMPLOYER_sign;

I load the image in these, and in a picturebox too:

    using (FileStream stream = new FileStream("C:/SCR/temp/sign.jpg", FileMode.Open, FileAccess.Read))
    {
        WORKER_sign = Image.FromStream(stream);
        stream.Close();
    }
    pictureBox3.Image = WORKER_sign;
    pictureBox3.SizeMode = PictureBoxSizeMode.Zoom;

The picturebox shows the images perfectly, however i can't write in a byte array. I tried the following code:

public static byte[] ImageToByte(Image img)
{
    if (img == null) return null;
    byte[] result;
    using (MemoryStream stream = new MemoryStream())
    {
        img.Save(stream, img.RawFormat);
        result = stream.GetBuffer();
    }
    return result;
}
byte[] temparray = ImageToByte(WORKER_SIGN);

But the last line throws me a Generic GDI+ exception, and before this the IntelliTrace shows some System.ObjectDisposedException ("Closed file") too.

What's wrong with my code? Thank you for all the help! :)

OFF: Sorry for my bad ENG...

EDIT: The errors:

Exception:Thrown: "Cannot access a closed Stream." (System.ObjectDisposedException) A System.ObjectDisposedException was thrown: "Cannot access a closed Stream." Time: 2014.08.11. 14:37:49 Thread:Main Thread[7276]

Exception:Thrown: "Generic error in: GDI+." (System.Runtime.InteropServices.ExternalException) A System.Runtime.InteropServices.ExternalException was thrown: "Generic error in: GDI+." Time: 2014.08.11. 14:37:49 Thread:Main Thread[7276]

Atanas Desev · Accepted Answer · 2014-08-11 12:36:19Z

3

Change your code to:

public static byte[] ImageToByte(Image img)
{
    if (img == null) return null;
    byte[] result;
    using (MemoryStream stream = new MemoryStream())
    {
        img.Save(stream, img.RawFormat);
        result = stream.ToArray();
    }
    return result;
}

answered Aug 11, 2014 at 12:36

Atanas Desev

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3 Comments

RAPTOR Over a year ago

img.Save(stream, img.RawFormat); throws the same exceptions :( But thank you :)

Dirk Over a year ago

@AtanasDesev The problem is not the code you posted but that the stream that was used to load the image was closed. Image.FromStream takes ownership of the stream and the stream must not be closed.

Atanas Desev Over a year ago

@Dirk Thank you, I just saw the exception in the update post.

RAPTOR · Accepted Answer · 2014-08-11 16:06:23Z

0

Thanks for everbody who helped me, I'm figured out the things by this code:

    EMPLOYER_SIGN = new Bitmap(426, 155);
    using (Graphics gr = Graphics.FromImage(EMPLOYER_SIGN))
    {
        gr.SmoothingMode = SmoothingMode.HighQuality;
        gr.InterpolationMode = InterpolationMode.HighQualityBicubic;
        gr.PixelOffsetMode = PixelOffsetMode.HighQuality;
        gr.DrawImage(Image.FromFile("C:/SCR/temp/sign.jpg"), new Rectangle(0, 0, 426, 155));
    }
    MemoryStream ms = new MemoryStream();
    EMPLOYER_SIGN.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
    BARRAY_EMPSIGN = ms.ToArray();
    ms.Dispose();
    pictureBox3.Image = EMPLOYER_SIGN;

answered Aug 11, 2014 at 16:06

RAPTOR

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