no, it is not necessary that the image field is pushed by the server:
all you need to do is to prepare a cell for your extra field (ie a cell with a field name/index that differs from fields sent by the server; note the # in the name of the field, it can be useful if you create you table "fetching" the schema from the html fields, see table constructors for details, eg
OverwriteTable)
[syntax="HTML"]<span source="lightstreamer" table="yourTable" item="yourItem" field="#image">-</span>[/syntax]
set your table to push html values through the
setPushedHtmlEnabled method (please read carefully the documentation of such method)
[syntax="JS"]yourTable.setPushedHtmlEnabled(true);[/syntax]
and finally put the html for your image in the table
[syntax="JS"]yourTable.onItemUpdate = function(pos,obj,name) {
//some code
obj.addField("#image","<img src='yourimage.gif' />");
//more code
}
[/syntax]
this is just a basic example, you could obviously use other approaches to show your image
