Ubuntu Manpage: ppmtoarbtxt - generate image in arbitrary text format from PPM image

NAME

       ppmtoarbtxt - generate image in arbitrary text format from PPM image

SYNOPSIS

       ppmtoarbtxt bodytmpl [-hd headtmpl] [-tl tailtmpl] [ppmfile]

DESCRIPTION

This program is part of Netpbm(1).

ppmtoarbtxt generates simple text-based graphics formats based on format descriptions
given as input. A text-based graphics format is one in which an image is represented by
text (like PNM plain format, but unlike PNM raw format).

ppmtoarbtxt reads a PPM image as input. For each pixel in the image, ppmtoarbtxt writes
the contents of the template file bodytmpl, with certain substitutions based on the value
of the pixel, to Standard Output.

You may also supply a head template file, in which case ppmtoarbtxt generates text from
the template file, based on the image dimensions, and includes it in the output before
anything else.

Likewise, you may supply a tail template file to cause text to be placed at the end of the
output.

Template Files
The text that ppmtoarbtxt generates from a template file is the literal text of the
template file, except with substitution specifier replaced with something else. The
program recognizes a substitution specifier as text of the form #(...).

ppmtoarbtxt treats white space in the template files the same as any other characters,
placing it in the output, with one exception: If the template file ends with a newline
character, ppmtoarbtxt ignores it -- it does not include it in the output.

Many substitution specifiers use format strings (another form of template) to specify the
substitution. You should make these format strings as minimal as possible, placing
literal text outside the substitution specifier instead of inside the format string. For
example,

Wrong: #(flum %%%2.2f 0 1)

Right: %#(flum %2.2f 0 1)

The valid substitution specifiers are as follows. Text that has the form of a
substitution specifier but is not actually valid (e.g. #(random junk) usually just
specifies its literal value, but if it is close enough to something valid, ppmtoarbtxt
assumes you made a mistake and fails.

Useful in a body template, to do substitutions based on a particular pixel:

#(ired format blackref whiteref)
generates an integer in the range blackref to whiteref in a format specified by
format representing the red intensity of the pixel. A red intensity of 0 becomes
blackref; a red intensity of maxval becomes whiteref, with the rest linearly
interpolated in between.

format is a printf-like format specifier like "%d". ppmtoarbtxt uses as the entire
format string to a fprintf POSIX library call whose only other argument is the red
itensity as an integer data type. ppmtoarbtxt does not necessarily verify that
your format string makes sense; there are values you could specify that could even
crash the program. To avoid unexpected behavior, keep format strings simple and
hardcoded, and never include a per cent sign or newline.

#(ired) is equivalent to #(ired %d 0 255).

#(igreen format blackref whiteref)
Same as #(ired..., but for green.

#(iblue format blackref whiteref)
Same as #(ired..., but for blue.

#(ilum format blackref whiteref)
Same as #(ired..., but representing the luminance value (0.299*red + 0.587*green +
0.114*blue) of the pixel.

#(fred format blackref whiteref)
Same as #(ired..., but generates a floating point number instead of an integer.

In this case, the second argument to the fprintf that uses format has a double
precision floating point data type.

#(fred) is equivalent to #(fred %f 0.0 1.0).

#(fgreen format blackref whiteref)
Same as #(fred..., but for green.

#(fblue format blackref whiteref)
Same as #(fred..., but for blue.

#(flum format blackref whiteref)
Same as #(fred..., but representing the luminance value (0.299*red + 0.587*green +
0.114*blue) of the pixel.

#(posx format)
Generates the horizontal position of the pixel, in pixels from the left edge of the
image.

The second argument to the fprintf that uses format has an unsigned integer data
type.

format defaults to %u

#(posy format)
Same as #(width..., but for the vertical position.

If you use any of the above substitution specifiers in a head or tail template, the result
is undefined.

Useful in a head or tail template, to do substitutions based on whole-image attributes:

#(width format)
Generates the width in pixels of the image.

The second argument to the fprintf that uses format has an unsigned integer data
type.

format defaults to %u

#(height format)
Same as #(width..., but for the height of the image.

OPTIONS

       In addition to the options common to all programs based on libnetpbm (most notably -quiet,
       see
        Common Options ⟨index.html#commonoptions⟩ ), ppmtoarbtxt recognizes the following command
       line options:

       -hd headtmpl
              This  option  specifies  a head template (headtmpl is the name of the head template
              file); it causes ppmtoarbtxt to place the contents of the file  named  headtmpl  at
              the beginning of the output

       -tl tailtmpl
              This option specifies a tail template; it is analogous to -hd.

EXAMPLES

   gray inversion
       Here we generate a PGM plain-format image with gray inversion (like ppmtopgm | pnminvert).

       Contents of our head template file:

       P2
       #(width) #(height)
       255

       Contents of our body skeleton file:

       #(ilum %d 255 0)

   povray file
       Here  we  generate  a  povray file where each pixel is represented by a sphere at location
       (x,y,z) = (posx,height-posy,luminance).  The color of the  sphere  is  the  color  of  the
       pixel.

       Contents of our head skeleton:

       #include "colors.inc"
       #include "textures.inc"
       camera {
          location  <#(width) * 0.6, #(height) * 0.7, 80>
          look_at   <#(width) * 0.5, #(height) * 0.5, 0>
       }

       light_source { <#(width) * 0.5, #(height) * 0.5, 25> color White
       }

       Contents of our body skeleton:

       sphere { <#(posx),#(height)-#(posy),#(ilum %d 0 10)>, 0.5
         texture {
           pigment {
             color rgb <#(fred),#(fgreen),#(fblue)>
           }
           finish {
             phong 1
           }
         }
       }

HISTORY

       ppmtoarbtxt  was added to Netpbm in Release 10.14 (March 2003).  It existed under the name
       ppmtotxt since 1995.

AUTHOR

       Copyright (C) 1995 by Peter Kirchgessner

DOCUMENT SOURCE

       This manual page was generated by the Netpbm tool 'makeman' from HTML source.  The  master
       documentation is at

              http://netpbm.sourceforge.net/doc/ppmtoarbtxt.html