NAME

       pamsummcol - summarize (sum, average, etc) a Netpbm image by column

SYNOPSIS

       pamsummcol { -sum | -mean | -min | -max } [imagefile]

       All  options  can be abbreviated to their shortest unique prefix.  You may use two hyphens
       instead of one.  You may separate an option name and its value with white space instead of
       an equals sign.

DESCRIPTION

       This program is part of Netpbm(1).

       pamsummcol  reads a Netpbm image (PNM or PAM) and performs a summary function over all the
       rows in each column (sum, mean, etc.).  It produces an image of the  same  kind  that  the
       same  width and depth as the input, and one row high.  Its sample values are the result of
       the summary.

       pamsummcol performs the summary operation on each plane independently.

       pamsummcol performs  the  operation  on  the  actual  sample  values,  not  on  the  light
       intensities represented by them in the case that the image is a PGM or PPM image.

       If  you want to summarize by row instead of by column, run the input through pamflip first
       (and if you want the output to be a single column instead of a  single  row,  use  pamflip
       again).

       If  you  want  to  summarize over the entire image (getting a one-tuple output image), use
       pamsumm to get a summary row, pamflip to turn that into a column,  the  pamsumm  again  to
       summarize the column.

       If  you  want to summarize the individual samples in an entire image, instead of by tuple,
       use pamsumm.

       pamsummcol performs  the  operation  on  the  actual  sample  values,  not  on  the  light
       intensities  represented  by  them in the case that the image is a PGM or PPM image or PAM
       equivalent.  You  can  use  pnmgamma  to  convert  such  an  image  to  one  with  samples
       proportional to light intensity, and then use pamsummcol on the result.

       You  can  achieve the same thing as pamsummcol -mean with pamscale.  Just scale vertically
       to a single row, without scaling horizontally at all.  Use the pixel mixing method.

OPTIONS

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

       You must specify exactly one of -sum, -mean, -min, or -max.

       -sum

              This option makes the summary function addition.
                   In each column and plane of the output row, the sample value is the
                   sum of all the samples values in the same column and plane of the input.
                   If a result is greater than the image maxval, it is clipped to
                   the maxval.

       -mean

              This option makes the summary function arithmetic mean.
                   In each column and plane of the output row, the sample value is the
                   mean of all the samples values in the same column and plane of the input.

       -min

              This option makes the summary function arithmetic minimum.
                   In each column and plane of the output row, the sample value is the
                   minimum of all the samples values in the same column and plane of
                   the input.

       -max

              This option makes the summary function arithmetic maximum.
                   In each column and plane of the output row, the sample value is
                   the maximum of all the samples values in the same column and
                   plane of the input.

SEE ALSO

       pamsumm(1), pamflip(1), pamfunc(1), pamarith(1), pamscale(1), pam(1),

HISTORY

       pamsummcol was added to Netpbm in Release 10.21 (March 2004).

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/pamsummcol.html