How to cast pictures to castnow on the Linux command-line?

I am able to cast videos to my chromecast device using castnow, but I haven't had any luck casting images. I tried to use a python cast library (pychromecast) in conjunction with the internal python HTTP server to serve images, but had no luck. I never saw a single request from the chromecast to the web server. However, if I accessed the webpage directly, I was able to see the images. Is it possible to tell the chromecast to display an image adhoc? Ideally, I'm looking for something that is python, java, c, shell script, etc. that can run on Linux.