You can easily display an image using the OLD Grafana v6 table panel (which you can still use in Grafana v7).
You just need to have the table display the relevant HTML img tag within a column and enable the Sanitize HTML option on the table column. So for a MySQL source the query would be something like:
select <img src="image_source_here" height="200"> as ‘Logo’
In theory you should be able to also use the Text panel with either markdown or HTML but I have not used that.