Flip or rotate a PAM or PNM image. More information: https://netpbm.sourceforge.net/doc/pamflip.html.
pamflip -rotate90|180|270 path/to/input.pam > path/to/output.pam
pamflip -leftright path/to/input.pam > path/to/output.pam
pamflip -topbottom path/to/input.pam > path/to/output.pam
pamflip -transpose path/to/input.pam > path/to/output.pam