pamtopng(1) on Linux
The text 8c3c53d53ba7, as Debian 12 (Bookworm) shipped it.
convert a Netpbm image to PNG
Flags it lists
-
-background -
-chroma -
-gamma -
-interlace -
-itxt -
-srgbintent -
-text -
-transparent -
-verbose -
-ztxt