You have to use generic handler.
Refer -
Showing image in GridView from the database?[
^].
So, in DataBound event of Gridview you can write something like below.
Image1.ImageUrl = "~/ShowImage.ashx?id=" + id;
Where
Image1 is the image control in the gridview and
id is the Foreign Key value like "Employee ID" in
Image Table (you can get this while databinding).
The handler will return you the whole image and will be shown in that image control directly.
More reference :
1.
Save and retrive Binarydata from database into image[
^].
2.
how to display image from sql table in gridview?[
^]