Version 3 of Image manipulation without Tk

[Explain motivation (cron, possible sneer at Java, portability, ...]

[Explain alternatives:

utility X server
Xvfb [L1 ]
VNC [L2 ]
tclgd
Image [L3 ]
Xbit [L4 ]
[xwd ...]
Pure Tcl solutions. An example DKF offered is

  #! /usr/local/bin/tclsh8.3
  puts "Content-Type: image/x-portable-graymap"
  puts ""
  puts "P2"                          ;# ASCII PGM "magic number"
  puts "10 10"                       ;# width and height
  puts "18"                          ;# Max grey value
  for {set i 0} {$i<10} {incr i} {
     set line ""
     for {set j 0} {$j<10} {incr j} {
        lappend line [expr {$i+$j}]
     }
     puts $line
  }
  exit