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 ), 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