How do I download image contained in PictureBox with database in C #?

I have a question that I can not solve and I am looking for your help ...

I comment, I have a datagrid which has a column type image in which I use as a preview of my image that is loaded from a database.

Often I have a button type column which I use to see the image in a PictureBox, all this works correctly I can see all the images in the picturebox when I click the View button.

Then I have a button type column to delete the image, that works correctly.

Then I have a column type button which has a button that is to download the image that has the picturebox and here is the problem.

Here the image of datagrid

Here I have the code of how to press the button see the image goes to the picturebox

DataGridViewImageCell cell = 
dataGridView2.Rows[e.RowIndex].Cells["vistaprev"] as DataGridViewImageCell;
Bitmap bmpbt;
bmpbt = (Bitmap)cell.Value;

using (MemoryStream ms = new MemoryStream())
{
bmpbt.Save(ms, ImageFormat.Jpeg);
base64dgv = Convert.ToBase64String(ms.ToArray());

MemoryStream msm = new  MemoryStream(Convert.FromBase64String(base64dgv));
pictureBox2.Image = Bitmap.FromStream(ms);
pictureBox2.SizeMode = PictureBoxSizeMode.StretchImage;
}  

So I'm trying to download the images ...

SaveFileDialog newsave = new SaveFileDialog();
            newsave.FileName ="Name";
            newsave.Filter = "JPEG(*.JPEG)|*.JPEG";


            if (newsave.ShowDialog() == DialogResult.OK)
            {

                pictureBox2.Image.Save(newsave.FileName,ImageFormat.Jpeg);
            }  

This downloads an image, but when I open it, the image is not displayed, just like this name.jpeg and when I give it a double cilck to see the image, nothing is seen.

They can guide me on how to do it.

Thanks.

Note: The image is loaded from the database, I NEVER PASS THE IMAGE PATH TO THE PICTUREBOX, do not get confused.