NAME

       ppmtoilbm - convert a PPM image into an ILBM file

SYNOPSIS

       ppmtoilbm

       [-maxplanes|-mp N]

       [-fixplanes|-fp N]

       [-ham6|-ham8]

       [{-dcbits|-dcplanes} r g b]

       [ -normal|-hamif|-hamforce|-24if|-24force| -dcif|-dcforce|-cmaponly ]

       [-ecs|-aga]

       [-compress|-nocompress]

       [-cmethod type]

       [-map ppmfile]

       [ppmfile]

DESCRIPTION

       This program is part of Netpbm(1).

       ppmtoilbm  reads  a  PPM  image  as  input.   Produces  an ILBM file as output.  ppmtoilbm
       understands the following ILBM types:

       •      Normal ILBMs with 1-16 planes

       •      Amiga HAM with 3-16 planes

       •      24 bit

       •      Color map (BMHD + CMAP chunk only, nPlanes = 0)

       •      Unofficial direct color.  1-16 planes for each color component.

       Chunks written: BMHD, CMAP, CAMG (only for HAM), BODY (not for colormap files)  unofficial
       DCOL chunk for direct color ILBM.

OPTIONS

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

       Options  marked with (*) can be prefixed with a "no", e.g. "-nohamif".  All options can be
       abbreviated to their shortest unique prefix.

       -maxplanes | -mp n
              (default 5, minimum 1, maximum 16) Maximum planes to write in a  normal  ILBM.   If
              the  image  does not fit into <n> planes, ppmtoilbm writes a HAM file (if -hamif is
              used), a 24bit file (if -24if is used) or a direct color file (if -dcif is used) or
              aborts with an error.

       -fixplanes | -fp b
              (min 1, max 16) If a normal ILBM is written, it will have exactly <n> planes.

       -hambits | -hamplanes n
              (default  6,  min  3, max 16) Select number of planes for HAM picture.  The current
              Amiga hardware understands 6 and 8 planes, so for now  you  should  only  use  this
              values.

       -normal
              Turns off -hamif/-24if/-dcif, -hamforce/-24force/-dcforce and -cmaponly.  Also sets
              compression type to byterun1.

              This is the default.

       -hamif (*)

       -24if (*)

       -dcif (*)
              Write a HAM/24bit/direct color file if the image  does  not  fit  into  <maxplanes>
              planes.

       -hamforce (*)

       -24force (*)

       -dcforce (*)
              Write a HAM/24bit/direct color file.

       -dcbits r g b

       -dcplanes r g b
              (default  5,  min  1,  max 16).  Select number of bits for red, green and blue in a
              direct color ILBM.

       -ecs   Shortcut for: -hamplanes 6 -maxplanes 5

              This is the default.

       -aga   Shortcut for: -hamplanes 8 -maxplanes 8

       -ham6  Shortcut for: -hamplanes 6 -hamforce

       -ham8  Shortcut for: -hamplanes 8 -hamforce

       -compress (*)
              This is the default.  Compress the BODY chunk.  The default compression  method  is
              byterun1.   Compression  requires  building  the  ILBM  image  in  memory;  turning
              compression off allows stream-writing of the image, but  the  resulting  file  will
              usually  be  30%  to  50% larger.  Another alternative is the -savemem option, this
              will keep memory requirements for compression at a minimum, but is very slow.

       -cmethod none|byterun1
              This option does the same thing as -compress.

       -map ppmfile
              Write a normal ILBM using the colors in <ppmfile> as the  colormap.   The  colormap
              file also determines the number of planes; -maxplanes and -fixplanes are ignored.

       -cmaponly
              Write a colormap file: only BMHD and CMAP chunks, no BODY chunk, nPlanes = 0.

       -savemem
              See the -compress option.

LIMITATIONS

       HAM  pictures will always get a grayscale colormap; a real color selection algorithm might
       give better results.  On the other hand, this allows row-by-row operation on  HAM  images,
       and  all  HAM  images  of the same depth (no. of planes) share a common colormap, which is
       useful for building HAM animations.

REFERENCES

       Amiga ROM Kernel Reference Manual - Devices (3rd Ed.)  Addison Wesley, ISBN 0-201-56775-X

SEE ALSO

       ppm(1), ilbmtoppm(1)

HISTORY

       For about a year in 1993-1994, there was a -savemem option.

       There used to be a -floyd (aka -fs) option that was supposed
         to cause images to be dithered so that a larger number of colors in the PPM
         input could be represented in a smaller number of colors in the ILBM output.
         But it was never documented.  Furthermore, developers discovered in January
         2022 that the code for this was nonfunctional because of defects, and had
         been for a very long time and maybe always.  Finally,, this functions is not
         appropriate in the Netpbm philosophy, because dithering should be done by a
         separate dithering program, not a format conversion program.  Indeed,
         the programs ppmdither, pnmquant, and pnmremap can do
         this.

       Therefore, since Netpbm 10.98 (March 2022), the dithering code has not been
         in the program and any attempt to use the options fails with a simple
         invalid option message.  But the -nofloyd and -nofs options
         remain, doing nothing as they were designed to do, and still not documented.
         This is just in case something uses those options, since the cost of
         maintaining them is so small.

AUTHORS

       Copyright (C) 1989 by Jef Poskanzer.

       Modified October 1993 by Ingo Wilken (Ingo.Wilken@informatik.uni-oldenburg.de)

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/ppmtoilbm.html