Using a checkbox outside of a datagrid to affect its contents

I am using a Checkbox outside of a datagrid. When i select the check box autopostback is true, and this would then show the image, but i cant access the images within the datagrid with that script. If i use a seperate image outside of the datagrid the script works. How can i get this script to work finding when the checkbox out side of the datagrid is checked to then show the image within the datagrid?

The script i am using is

<script runat="server">
 
     Sub Check(sender As Object, e As EventArgs)
         If checkShowImages.Checked Then
                 img.Visible = True
 
         Else
             img.Visible = False
         End If
     End Sub
 
 </script>
 

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