Not entirely sure how you set your surveys up or distribute them, but I'll give this a shot!
We pre-populate surveys year over year for returning respondents using the raw data from the previous year and uploading it as a new contact panel in the Directory. This lets us have multiple attributes (that are really just the previous years answers) customized for each respondent. *Note: anon surveys are just a blank survey. I have not played with having a custom image for each respondent, but the principle is the same.
If you have an external-facing media server, you could do full url paths to a hosted location to pull in the image for each participant. Otherwise, you could go into your Library -> Graphics Library, select the file, and copy the url. This would mean you'd have to upload all images you'd like to be available for survey respondents, but it should work. You would either then set these using a Mailing List or you set them in the embedded data section I believe. Or maybe with some branching logic in Survey Flow, based on who's taking the survey.

What JeremyK said. The only caveat I would offer is to beware of large image files, animations, or urls that will draw from external sources which could present a mix of security, usability, and accessibility issues.

Thanks a lot, JeremyK for the great suggestions! And thanks a lot, AdamK12 for the important reminder! Super helpful!