Provided by: netpbm_11.10.02-1build1_amd64 
NAME
pamundice - combine grid of images (tiles) into one
EXAMPLE
$ pamdice myimage.ppm -outstem=myimage_part -width=10 -height=8
$ pamundice myimage_part_%1d_%1a.ppm -across=10 -down=8 >myimage.ppm
$ pamundice myimage_part_%2a -across=13 -hoverlap=9
See pamdice for more examples.
SYNOPSIS
pamundice
{ [-across=n]
[-down=n] , -indexfile=pamfilename }
[-hoverlap=pixels]
[-voverlap=pixels]
[-verbose]
{input_filename_pattern, -listfile=textfilename}
You can use the minimum unique abbreviation of the options. You can use two hyphens instead of one. You
can separate an option name from its value with white space instead of an equals sign.
DESCRIPTION
This program is part of Netpbm(1).
pamundice reads a bunch of Netpbm images as input and combines them as a grid of tiles into a single
output image of the same kind on Standard Output.
You can optionally make the pieces overlap.
The images can either be in files whose names indicate where they go in the output (e.g.
'myimage_part_03_04' could be the image for Row 3, Column 4 - see the input_filename_pattern argument) or
listed in a file, with a -listfile option.
The input images must all have the same format (PAM, PPM, etc.) and maxval and for PAM must have the
same depth and tuple type. All the images in a rank (horizontal row of tiles) must have the same height.
All the images in a file (vertical column of tiles) must have the same width. But it is not required
that every rank have the same height or every file have the same width.
pamdice is the inverse of pamundice. You can use pamundice to reassemble an image sliced up by pamdice.
You can use pamdice to recreate the tiles of an image created by pamundice, but to do this, the original
ranks must all have been the same height except for the bottom one and the original files must all have
been the same width except the right one.
One use for this is to process an image in pieces when the whole image is too large to process. For
example, you might have an image so large that an image editor can't read it all into memory or processes
it very slowly. You can split it into smaller pieces with pamdice, edit one at a time, and then
reassemble them with pamundice.
Of course, you can also use pamundice to compose various kinds of checkerboard images, for example, you
could write a program to render a chessboard by computing an image of each square, then using pamundice
to assemble them into a board.
An alternative to join images in a single direction (i.e. a single rank or a single file) is pamcat.
pamcat provides alternative ways to identify the input images: you can supply them serially on Standard
Input or list them by name as command line arguments.
To join piecewise photographs, use pnmstitch instead of pamundice, because it figures out where the
pieces overlap, even if they don't overlap exactly vertically or horizontally.
To create an image of the same tile repeated in a grid, that's pnmtile.
pnmindex does a similar thing to pamundice: it combines a bunch of small images in a grid into a big one.
But its purpose is to produce an index image of the input images. So it leaves space between them and
has labels for them, for example.
ARGUMENTS
Unless you use a -listfile option, there is one non-option argument, and it is mandatory:
input_filename_pattern. This tells pamundice what files contain the input tiles.
pamundice reads the input images from files which are named with a pattern that indicates their positions
in the combined image. For example, tile_00_05.ppm could be the 6th tile over in the 1st rank, while
tile_04_01 is the 2nd tile over in the 5th rank.
(But see -indexfile, which can cause the tiles to be rearranged so that the file whose name indicates it
is the 6th tile over in the 1st rank could actually be placed by pamundice in any arbitrary position in
its output).
You cannot supply any of the data on Standard Input, and the files must be the kind that pamundice can
close and reopen and read the same image a second time (e.g. a regular file is fine; a named pipe is
probably not).
input_filename_pattern is a printf-style pattern. (See the standard C library printf subroutine). For
the example above, it would be tile_%2d_%2a.ppm. The only possible conversion specifiers are:
d "down": The rank (row) number, starting with 0.
a "across": The file (column) number, starting with 0.
% The per cent character (%).
The number between the % and the conversion specifier is the precision and is required. It says how many
characters of the file name are described by that conversion. The rank or file number is filled with
leading zeroes as necessary.
So the example tile_%2d_%2a.ppm means to get the name of the file that contains the tile at Rank 0, File
5, you:
• replace the "%2d" with the rank number, as a 2 digit decimal number: "00"
• Replace the "%2a" with the file number, as a 2 digit decimal number: "05"
Note that this pattern describes file names that pamdice produces, except that the precision may be more
or less. (See the -numberwidth option of pamdice).
OPTIONS
In addition to the options common to all programs based on libnetpbm (most notably -quiet, see Common
Options ), pamundice recognizes the following command line options:
-across=N
This is the number of tiles across in the grid, i.e. the number of tiles in each rank, or the
number of files.
You cannot specify this together with -indexfile.
Default is 1.
-down=N
This is the number of tiles up and down in the grid, i.e. the number of tiles in each file, or the
number of ranks.
You cannot specify this together with -indexfile.
Default is 1.
-hoverlap=pixels
This is the amount in pixels to overlap the tiles horizontally. pamundice clips this much off the
right edge of every tile before joining it to the adjacent image to the right. The tiles along
the right edge remain whole.
There must not be any input image narrower than this.
Note that this undoes the effect of the same -hoverlap option of pamdice.
Default is zero -- no overlap.
-voverlap=pixels
This is analogous to -hoverlap, but pamundice clips the bottom edge of each image before joining
it to the one below.
-listfile=textfilename
This option names a file that contains the names of all the input files. This is an alternative
to specifying a file name pattern as an argument.
The named file contains file names, one per line. Each file contains the
image for one tile, in row-major order, top to bottom, left to right. So
the first file is the upper left tile, the second is the one to right of
that, etc. The number of lines in the file must be equal to the number of
tiles in the output, the product of the -across and -down
values.
The file names have no meaning to pamundice. You can list the same
file multiple times to have identical tiles in the output.
If you create the tile files with pamdice, you can use the -listfile option of pamdice to produce
a suitable list file for reassembling the tiles into the same positions they had in the original
large image.
You cannot specify this together with -indexfile.
This option was new in Netpbm 10.90 (March 2020).
-indexfile=pamfilename
This option names a file that contains a PAM image that tells which tile files to put where in the
assembled output. See the pamfile -indexfile option for details on its format.
A typical way to generate an index image to use with pamundice is to use the -indexfile option of
pamdice, and then possibly manipulate the resulting index image with other Netpbm tools.
While the sample values in the index image are defined to be rank and file positions in some
original large image, and so are documented in those terms, in practice, pamundice doesn't assign
any meaning to the numbers -- they are just substitutions for two variables in the input file name
pattern (given as a program argument).
The maxval of the index image is irrelevant, except that no sample in the index image can be
greater than it.
The depth of the index file must be at least two (rank and file), but the program ignores any
additional planes.
The program ignores the tuple type.
If you don't specify this option, the position of a tile in the ouput is given directly by the
rank and file portions of the tile file name, or if you specify -listfile, by order in which the
tile files are listed in the list file.
You cannot specify this together with -listfile, -down, or -across.
This option was new in Netpbm 11.10 (March 2025).
-verbose
This says to print information about the processing to Standard Error.
Usage
Here is an example of using a list file:
Example usage of -listfile:
pamdice -width=100 -height=100 -outstem=img_part -listfile=listfile \
img.ppm
pamundice -listfile=listfile -across=6 -down=4 > img_copy.ppm
Note that in the above example, you have to know somehow that you got 6 files and 4 ranks from pamdice
and then specify the correct -across and -down options on pamundice. A slight error ruins the process.
A better way is to use -indexfile:
pamdice -width=100 -height=100 -outstem=img_part \
-numberwidth=3 -indexfile=index.pam img.pam
pamundice -indexfile=index.pam img_part_%3d_%3a.pam > img_copy.pam
Here is an example of flipping a large image. pamflip often requires the entire image to be in real
memory at once, which can be impossible or impractical with a very large image. This method does it in
smaller pieces so as to require less memory:
Example of -indexfile with pamflip operation:
pamdice -width=2500 -height=2500 -outstem=tile \
-numberwidth=3 -indexfile=index.pam hugeImage.ppm
# flip every tile
for tile in tile_???_???.ppm
do
pamflip -r180 $tile > ${tile%.ppm}.flipped.ppm
done
# flip indexfile - Simply apply the same flip operation
pamflip -r180 index.pam > index_flipped.pam
pamundice -indexfile=index_flipped.pam tile_%3d_%3a.flipped.ppm \
> hugeImage_flipped.ppm
HISTORY
pamundice was new in Netpbm 10.39 (June 2007). Before that, pamcat is the best substitute.
SEE ALSO
pamdice(1), pamcat(1), pnmindex(1), pnmtile(1), pnmtile(1), pnm(1), pam(1)
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/pamundice.html
netpbm documentation 08 February 2025 Pamundice User Manual(1)