Currently you can export the image without the info-popup, which is additional asset that is shown when user interacts with the chart. What could be done is that you can use html2canvas to render canvas + additional html elements to image string. Depending on if the the export is made by user or automated on server side, you could use different approaches.
If the user interacts with the chart, you could setup a keyboard shortcut which would invoke the html2canvas code which would export the image and the popup to an images. If you want to automate that on the server side, you would have to simulate mouseover event in a headless browser (eg. phantom), and then call the html2canvas code to export the image with the additional html assets.
p.s. @Edgars, I think this would be a good idea to have info popup as part of the canvas and also have an API call to trigger the display of the info popup.