Updated:
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