E.g. you have Gridview1 with 3 columns picturid,picturname,picture.
<asp:templatefield xmlns:asp="#unknown">
<itemtemplate>/*3rd column of gridview*/
<asp:image id="Image1" imageurl="~/images/ab.jpg" runat="server" />
</itemtemplate>
</asp:templatefield>
RowDataBound event of your gridview:
protected Gridview1_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
Image desired_image = (Image)e.Row.Cells[2].FindControl("Image1 ");
}
}