


IMRLA(3IM)             SDSC IMAGE LIBRARY              IMRLA(3IM)



NAME
     imrla - Wavefront RLA and RLB file translation

SYNOPSIS
     #include <stdio.h>
     #include "sdsc.h"
     #include "im.h"

     int ImFileRead( fd, "rla", flagsTable, dataTable )
          int         fd;
          TagTable   *flagsTable;
          TagTable   *dataTable;

     int ImFileFRead( fp, "rla", flagsTable, dataTable )
          FILE         *fp;
          TagTable   *flagsTable;
          TagTable   *dataTable;

     int ImFileWrite( fd, "rla", flagsTable, dataTable )
          int         fd;
          TagTable   *flagsTable;
          TagTable   *dataTable;

     int ImFileFWrite( fp, "rla", flagsTable, dataTable )
          FILE         *fp;
          TagTable   *flagsTable;
          TagTable   *dataTable;


DESCRIPTION
     rla image files are  generated  by  Wavefront  Technologies,
     Inc.,  software  such  as  image and tdv.  See the Wavefront
     documentation for information on how to use these and  other
     Wavefront programs.

     rla is a subset of the newer  Wavefront  rlb  specification.
     Programs that can read and write rlb files can also read and
     write rla files.  The SDSC image  library  reader/writer  is
     written to accommodate both types of files.

FILE RECOGNITION
     Wavefront rla files are recognized by the following filename
     suffixes:  .rla and .rlb.

NOTES
     SDSC image library support of the Wavefront rla format  does
     not  require  use  of  any  Wavefront  tools and contains no
     proprietary code. Wavefront rla is available on any  machine
     for which the SDSC image library is available.

  Reading Wavefront RLA files
     The  SDSC  image  library  reads  runlength-encoded   (RLE),



SDSC              Last change: August 24, 1992                  1






IMRLA(3IM)             SDSC IMAGE LIBRARY              IMRLA(3IM)



     scanline-interlaced,  24-bit  RGB and 32-bit RGB-Alpha Wave-
     front files and  maps  them  to  IMVFBRGB  and  (IMVFBRGB  |
     IMVFBALPHA) VFBs without color lookup tables (CLTs).

  Writing Wavefront RLA files
     Image library IMVFBRGB VFBs with or without alpha planes are
     written  to  runlength-encoded,  scanline-interlaced, 32-bit
     RGB-Alpha Wavefront rla files.  If the incoming VFB does not
     have  an  alpha  plane, outgoing image file alpha values are
     all set to 255.  Noninterlaced  and  plane-interlaced  modes
     are not supported by Wavefront rla files.

     Other image library VFB types are converted to  (IMVFBRGB  |
     IMVFBALPHA)   prior   to   being   written   out.   See  the
     ImFileWrite(3IM) man page for details.

     Note that the Wavefront rla specification requires the pres-
     ence  of an alpha channel in an rla image file, yet at least
     one of the Wavefront programs does not include  alpha  chan-
     nels in the images that it writes to files.

ERRORS
     In addition to those listed for  ImFileRead(3IM),  Wavefront
     rla file reading returns the following error codes:

          IMEMALLOC   Cannot allocate enough memory
          IMESYNTAX   Syntax error
          IMESYS      System call error in read operation

     In addition to those listed for ImFileWrite(3IM),  Wavefront
     rla file writing returns the following error codes:

          IMEMALLOC   Cannot allocate enough memory
          IMESYS      System call error in write operation

DOCUMENTATION
     _W_a_v_e_f_r_o_n_t _R_L_A _S_p_e_c_i_f_i_c_a_t_i_o_n, Wavefront Technologies, Inc.

SEE ALSO
     ImIntro(3IM),   ImErrNo(3IM),   imconv(1IM),    imfile(1IM),
     imformats(1IM)

AUTHOR
     T. Todd Elvins
     San Diego Supercomputer Center

CONTACT
     SDSC consultants, (619)534-5100, consult@y1.sdsc.edu







2                 Last change: August 24, 1992               SDSC



