NAME

       pamrestack - Rearrange rows of a Netpbm image

SYNOPSIS

       pamrestack

       [-width=width]

       [-trim={fill|crop|abort}]

       [-verbose]

       [pamfile]

       Minimum  unique  abbreviations  of  option  are acceptable.  You may use double hyphens instead of single
       hyphen to denote options.  You may use white space in place of the equals sign to separate an option name
       from its value.

DESCRIPTION

       This program is part of Netpbm(1).

       pamrestack  rearranges  the  pixels  of a Netpbm image into different size rows.  E.g. if an image is 100
       pixels wide and 50 pixels high, you can rearrange it to 125 wide and 40 high.  In that  case,  25  pixels
       from  the  start of the 2nd row of the input would be moved to the end of the 1st row of input, 50 pixels
       from the 3rd row would be moved to the 2nd row, etc.

       Put another way, pamrestack arranges all the input rows into one long sequence and produces  output  rows
       therefrom, in FIFO order.

       Input is from Standard Input if you don't specify the input file pamfile.

       Output is to Standard Output.

       pamrestack  works on a multi-image stream.  It cuts each image in the stream independently and produces a
       multi-image stream output.

OPTIONS

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

       -width=width
              The width of the output.  If this option is not specified, the output will
                consist of a single row wide enough to contain all the pixels of the input
                image.

       -trim={fill|crop|abort}
              This option specifies what to do when the new width does not cleanly divide the number  of  pixels
              in the input image.

       fill

              (Default) Complete the final row by adding black pixels as necessary.

       crop

              Discard the final partial row.  If this means there is nothing to
                  output, fail the program.

       abort

              Fail the program..

       -verbose
              Print information about the processing to Standard Error.

USAGE

       pamrestack is a general editor with many possible uses.

       •

                  pamrestack can rearrange into rectangles single-dimension images
                  produced by programs such as ppmhist and pamseq.  This makes
                  the output easier to examine with a viewer.  Conversely, pamrestack
                  can be used to convert a normal rectangular image into one wide row or one
                  tall column if that is desirable for compression, conversion, or analysis.

       •

                  pamrestack can repair images corrupted by an incorrect width value
                  in the header.  Images grabbed from the framebuffer device often exhibit
                  this problem.

       •      pamrestack can be used with pamdice, pamundice,
                  pamcat, etc. to divide and combine images in the process of
                  interlacing.

EXAMPLES

       •      Rearrange the one-dimensional output of pamseq into a square:

              pamseq 3 255 | pamrestack -width=4096

       •      Combine two files, each 600 pixels wide, one with the odd rows and
                another with the even rows, to construct an interlaced image:

              pamcat -leftright oddrows.ppm evenrows.ppm | pamrestack -width=600

       •      Like the above, but invert all pixels in the even rows left to right
                to produce a serpentine interlace:

                pamflip -leftright evenrows.ppm |
                  pamcat -leftright oddrows.ppm - |
                    pamrestack -width 600

SEE ALSO

       pamseq(1),  ppmhist(1), pnmshear(1), pamscale(1), pamdeinterlace(1), pamdice(1), pamundice(1), pamcat(1),
       pam(1)

HISTORY

       pamrestack was new in Netpbm 10.99 (June 2022).

AUTHOR

       By Akira F. Urushibata.  Contributed to the public domain by the author.

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/pamrestack.html