


IMCLTROLL(1IM)             IMAGE TOOLS             IMCLTROLL(1IM)



NAME
     imcltroll  -  Roll color lookup table by a number of entries

SYNOPSIS
     imcltroll [_o_p_t_i_o_n_s] _i_n_f_i_l_e_n_a_m_e _o_u_t_f_i_l_e_n_a_m_e

DESCRIPTION
     imcltroll reads each image in the input file,  extracts  the
     color  lookup  table, rolls it, then writes it and its image
     to the output file.  The input and output image file formats
     may be different.

OPTIONS
     imcltroll has a variety of options  in  the  following  five
     categories:

          File Selection     What input and output files to use
          Format Selection   What image file format to use
          Format Control     What variant of a file format to generate
          Standard           Standard generic options on all SDSC tools
          Rolling            How the image's CLT is rolled

     _F_i_l_e _S_e_l_e_c_t_i_o_n, _F_o_r_m_a_t _S_e_l_e_c_t_i_o_n, _F_o_r_m_a_t _C_o_n_t_r_o_l, and  _S_t_a_n_-
     _d_a_r_d options are common to all SDSC image tools and are dis-
     cussed in depth in the man page for imconv(1IM).

     All options can be abbreviated to the first few unique char-
     acters.

  Rolling Options
     Rolling a color lookup table, or  CLT,  copies  entry  0  to
     entry  _n, entry 1 to entry _n+1, entry 2 to entry _n+2, and so
     on.  Entries that roll off the bottom of the CLT wrap around
     back  to the top of the CLT, creating a rolling, or cycling,
     effect in the copy.

     The -roll _n option selects rolling of the CLT by _n  entries.
     Positive  values  for  _n  roll entries downwards towards the
     bottom of  the  CLT,  while  negative  values  roll  entries
     upwards towards the top.

     The input file must contain images that use  CLTs,  such  as
     color-indexed  images.   RGB images, for instance, typically
     do not have CLTs and are inappropriate for use by imcltroll.

NOTES
     CLT rolling is  a  technique  used  to  find  and  highlight
     aspects  of  an image generated, for example, by a CAT-scan.
     Different color indexes in a  CAT-scan  correspond  to  dif-
     ferent  types  of matter, such as bone, muscle, and air.  To
     highlight just the bone, a CLT may be constructed that  sets
     a  range  of color indexes to, say, bright red, and sets the



SDSC              Last change: October 13, 1992                 1






IMCLTROLL(1IM)             IMAGE TOOLS             IMCLTROLL(1IM)



     rest to black.

     When the red range of the CLT corresponds to the  CAT-scan's
     bone  indexes,  then  all  boney  matter  in  the  image  is
     highlighted in red.  To highlight a different set  of  image
     color  indexes,  roll  the  CLT far enough to bring the reds
     into the right index range, such as those  for  muscle.   By
     sweeping  the red values back and forth through the CLT, one
     can zero in on color indexes of interest.

     In rare, specialized applications, RGB images may have color
     lookup  tables.   In  these  cases, imcltroll will correctly
     roll the RGB image's color lookup table, store it, and place
     the  RGB image back into the output file.  However, many RGB
     image display tools choose to ignore  CLTs  associated  with
     RGB  images.   These  tools will fail to show the effects of
     rolling the color lookup table.  This is the  fault  of  the
     RGB image display tool, and not imcltroll.

     Sometimes RGB images have color  lookup  tables.   When  you
     rotate  the  color  lookup  table,  you may not perceive any
     changes in the image since some display programs  may  throw
     this  color  lookup  table out and use just the RGB informa-
     tion.

     For notes regarding  file  format  conversion  and  standard
     image tool options, see the man page on imconv(1IM).

     With no roll arguments, the actions of imcltroll default  to
     the   same   as   the  SDSC  image  format  conversion  tool
     imconv(1IM), but they take a little longer.

     Error messages are reported to stderr.

EXAMPLES
     Roll an XWD image's color lookup table by 30 entries:

          imcltroll in.xwd -roll 30 out.xwd

     Roll a color indexed Sun rasterfile backwards 5 entries  and
     store the result as a GIF file:

          imcltroll in.ras -roll -5 out.gif

SEE ALSO
     imroll (1IM), ImCltRoll (3IM)

     For information on SDSC's image library, see imintro(3IM).

     For information on the individual image  file  formats,  see
     their  respective man pages: imbmp (3IM), imcur (3IM), imeps
     (3IM), imgif (3IM), imhdf (3IM), imico (3IM), imicon  (3IM),



2                 Last change: October 13, 1992              SDSC






IMCLTROLL(1IM)             IMAGE TOOLS             IMCLTROLL(1IM)



     imiff  (3IM),  immpnt (3IM), impbm (3IM), impcx (3IM), impgm
     (3IM), impic (3IM), impict (3IM), impix (3IM), impnm  (3IM),
     imppm  (3IM),  imps  (3IM),  imras (3IM), imrgb (3IM), imrla
     (3IM), imrle  (3IM),  imrpbm  (3IM),  imrpgm  (3IM),  imrpnm
     (3IM),  imrppm  (3IM),  imsynu  (3IM),  imtga  (3IM), imtiff
     (3IM), imviff (3IM), imx (3IM), imxbm (3IM), imxwd (3IM)

AUTHOR
     Chris Groening
     San Diego Supercomputer Center

     See the individual file format man pages for the authors  of
     the  underlying  format  read  and write code.  The names of
     these man pages begin with the letters "im," followed by the
     format  name.  For example, the name of the TIFF man page is
     imtiff.  To display it, enter man imtiff.

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




































SDSC              Last change: October 13, 1992                 3



