pamtopng(1) on Linux
The text 5ef33915fa11, as Debian 13 (Trixie) shipped it.
convert a Netpbm image to PNG
Flags it lists
-
-background -
-chroma -
-gamma -
-interlace -
-itxt -
-srgbintent -
-text -
-transparent -
-verbose -
-ztxt