slack transparent profile image

You can't have a transparent profile avatar image in Slack in 2022-11-29 :(

This was requested in 2014, but did not change in 2017 and 2022: https://twitter.com/slackhq/status/533006882588622848

Manually set an image via curl (if you have a token):

curl -s -XPOST https://slack.com/api/users.setPhoto --form token=xoxp-secret --form image=@myimage.png