My tcl (8.5) is not the lates, and this version does not support png, as the following script demonstrates: I could use gif images, but I do not think it is common practice (and I can not make them look nice). What would be standard practice here? Unfortunately I couldn't find any practical advice around that fits my case. Any suggestion is welcome. I am on macOS.

Use bitmaps (bmp)? Use jpegs? Upgrade to Tcl that supports png?