how can i control images in an aspnet app?

So, you want to hide the image if certain data has certain value. You, can simply compare the value and apply a css class as hidden to that element like:

First, add this css in the head element.

.d-none {
    display: none !important;
}

Then replace your image control with this markup:

<asp:ImageButton runat="server" ID="imgInfo" CssClass='<%# Eval("SomeColumn") == DBNull.Value ? "d-none" : "" %>' ImageUrl="~/Images/info-note.png" tooltip='<%# Eval("user_address").ToString().Trim() %>' style="position: center; top: 3px; padding-right: 3px; padding-left:5px;cursor: help;" />

You can replace SomeColumn with the database column that contains your value to be compared and I just compared if it was null, you can do other comparisons as well.

UPDATE

You can add another clause in the comparison and we can use string.IsNullOrEmpty() method to check if the varchar column is empty.

<asp:ImageButton runat="server" ID="imgInfo" CssClass='<%# Eval("SomeColumn") == DBNull.Value || string.IsNullOrEmpty(Eval("SomeColumn").ToString()) ? "d-none" : "" %>' ImageUrl="~/Images/info-note.png" tooltip='<%# Eval("user_address").ToString().Trim() %>' style="position: center; top: 3px; padding-right: 3px; padding-left:5px;cursor: help;" />