Portable Pix Map, an image format of the PNM family.  It is a part of
[PBM Plus] - a large numbers of image converters and manipulators available
on the internet.

Every pixel is represented by three bytes for red, green, and blue channel. No compression, no transparency, as far as [RS] is aware.

[Tk] images can be read and written in PPM format using [photo] [[as of which version?]].  See also [PGM].

[CRIMP] can read and write PPM images.

[RS] 2006-06-02: Here is a reader that parses a "P3" format PPM string (like read from a file) and creates a [photo] from it:

 proc ppm-photo ppm {
   regsub -all {#[^\n]*\n} $ppm " " ppm ;# strip out comments
   foreach {type w h max} $ppm break
   foreach {r g b} [lrange $ppm 4 end] {
      set r [expr {int(255.*$r/$max)}]
      set g [expr {int(255.*$g/$max)}]
      set b [expr {int(255.*$b/$max)}]
      lappend row [format #%02X%02X%02X $r $g $b]
      if {[llength $row] == $w} {
         lappend rows $row
         set row {}
      }
   }
   set im [image create photo]
   $im put $rows
   set im
 }
#-- Testing:
 set data {P3
 4 4
 15
 0 0 0 0 0 0 0 0 0 15 0 15
 0 0 0 0 15 7 0 0 0 0 0 0
 0 0 0 0 0 0 0 15 7 0 0 0
 15 0 15 0 0 0 0 0 0 0 0 0
 }
 ppm-photo $data
#-- produces the following image (zoomed by a factor of 9):
[WikiDbImage ppm.jpg]
A larger ray-tracing image to test with is at http://www.cpsc.ucalgary.ca/~cherlin/sample.ppm [[[AMG]: 404]] - I was happy to see that IrfanView and my little [proc] agreed on how to render it :^)

[aricb] From P3 PPM to photo image in 17 lines!  I'm impressed.

[AMG]: Why are floating-point numbers used in the RGB scaling code?  The following is equivalent, simpler, and faster:

======
      set r [expr {255*$r/$max)}]
      set g [expr {255*$g/$max)}]
      set b [expr {255*$b/$max)}]
======

Test:

======
for {set max 1} {$max < 1024} {incr max} {
    for {set i 0} {$i < $max} {incr i} {
        if {int(255.*$i/$max) != 255*$i/$max} {puts "$i/$max"}
    }
}
======

This code never prints, so there is never a discrepancy, for all valid RGB values (in $i) for all $max values from 1 through 1024.

----
'''[AK] - 2010-08-12 11:19:57'''

Unknown about the floating point stuff. I put a derivative of this into [CRIMP] and used integer math without problems.


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