You can add an image into a SpreadSheet cell using the addImage method. There are three parameters that you should apply: rowId (number of the row), columnId (number of the column), URL (the URL of an image). Check out a free programming example of how it works below.
webix.ready(function(){ webix.ui({ view:"spreadsheet", id: "ssheet", toolbar: "full", data:{ styles: [ [ "blue", "#FFFFFF;#2244DE;" ] ], sizes: [ [ 3, 0, 50 ] ], data: [] } }); $$("ssheet").addImage(3, 2, "http://docs.webix.com/media/desktop/icons/spreadsheet.png"); });