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Pamrestack User Manual(1) General Commands Manual Pamrestack User Manual(1)



pamrestack - Rearrange rows of a Netpbm image







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.


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.


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:

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

This option specifies what to do when the new width does not cleanly divide the number of pixels in the input image.

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

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

Fail the program..

Print information about the processing to Standard Error.


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


  • 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


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


pamrestack was new in Netpbm 10.99 (June 2022).


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


This manual page was generated by the Netpbm tool 'makeman' from HTML source. The master documentation is at
netpbm documentation