User:Andrew Nikitin/pnm

Netpbm

PBM is for bitmaps (black and white, no grays) PGM is for grayscale PPM is for "pixmaps" which represent full RGB color

header

P1 Portable bitmap ASCII

P1
# This is an example bitmap of the letter "J"
6 10
0 0 0 0 1 0
0 0 0 0 1 0
0 0 0 0 1 0
0 0 0 0 1 0
0 0 0 0 1 0
0 0 0 0 1 0
1 0 0 0 1 0
0 1 1 1 0 0
0 0 0 0 0 0
0 0 0 0 0 0

P2 Portable graymap ASCII

P2
# Shows the word "FEEP" (example from Netpbm main page on PGM)
24 7
15
0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
0  3  3  3  3  0  0  7  7  7  7  0  0 11 11 11 11  0  0 15 15 15 15  0
0  3  0  0  0  0  0  7  0  0  0  0  0 11  0  0  0  0  0 15  0  0 15  0
0  3  3  3  0  0  0  7  7  7  0  0  0 11 11 11  0  0  0 15 15 15 15  0
0  3  0  0  0  0  0  7  0  0  0  0  0 11  0  0  0  0  0 15  0  0  0  0
0  3  0  0  0  0  0  7  7  7  7  0  0 11 11 11 11  0  0 15  0  0  0  0
0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0

P3 Portable pixmap ASCII

P3
# The P3 means colors are in ASCII, then 3 columns and 2 rows,
# then 255 for max color, then RGB triplets
3 2
255
255   0   0     0 255   0     0   0 255
255 255   0   255 255 255     0   0   0

P4 Portable bitmap Binary P5 Portable graymap Binary P6 Portable pixmap Binary [{{#file: "pnm.ijs"}} Download script: pnm.ijs ]

readpnm=:3 : 0
  d=.1!:1 boxopen y
  skip=.0

  type=.'' NB. pnm subtype
  s=.i.0 NB. size
  max=.0 NB. max component
  while. 1 do.
    l=.LF i.~ skip }. (skip+256){. d
    txt=.skip}.(skip+l){.d
    skip=.skip+1+#txt
    if. (-.'#'={.txt) *. -. ''-:txt do.
      if. ''-:type do.
        type=.txt
      elseif. 0=#s do.
        s=.|. _". txt
        assert. 2=#s
        assert. _>>./s
        if. ('P1'-:type) +. ('P4'-:type) do. break. end.
      elseif. 0=max do.
        max=._ ". txt
        assert. max>0 NB. positive
        assert. max<_ NB. valid
        assert. 0=#$max NB. scalar
        break.
      elseif. 1 do.
        'impossible' assert. 0
      end.
    end.
  end.
  d=.skip}.d
  if. type-:'P4' do.
    'hei wid'=.s
    wid{."1 (hei,(+8|-)wid)$,(8#2)&#: a. i. d
  elseif. type-:'P5' do.

    if. 255-:max do.
      s$ a.i.d
    else.
      s$ <.@*&(255%max)) a.i.d
    end.
    NB. multiply by 16b010101 to get rgb
  elseif. type-:'P6' do.
    if. 255-:max do.
      s$_3 (256&#.)\,a.i.d
    else.
      s$_3 (256 #. <.@*&(255%max))\,a.i.d
    end.
  elseif. type-:'P1' do.
    s$(+. # [)/ '10' =/ d
  elseif. 1 do.
    'Unsupported pnm subformat' assert. 0
  end.
)

writepbm=:writepbm4

writepbm4=:4 : 0
  y=.boxopen y
  y 1!:2~ 'P4',LF,(":|.$x),LF, _8 (a.{~#.)\ , ({.~ (] + 0 >. 0 8| -)@$) x
)

writepbm1=:4 : 0
  y=.boxopen y
  y 1!:2~ 'P1',LF,(":|.$x),LF
  _70 ([: (1!:3&y) ,&LF)\ ,x{'01'
)

writeppm6=:4 : 0
  y=.boxopen y
  y 1!:2~ 'P6',LF,(":|.$x),LF,'255',LF
  y 1!:3~ a.{~,256 256 256 #: x
)