splitblend(1) General Commands Manual splitblend(1)
NAME
splitblend - Produce command files for running blendmont in parallel
SYNOPSIS
splitblend [options] Blendmont_command_file
DESCRIPTION
Splitblend is a Python script that takes a command file for running
Blendmont and produces files that can be run in parallel with Pro-
cesschunks(1). Blendmont performs two distinct operations. First,
it finds the displacement between adjacent pieces and the detailed map-
pings between pieces in their overlap zones; the latter are referred to
as edge functions. Second, it uses this information to make the
blended images. The first operation can only be divided into two
parts, one for all of the edges between pieces in the X direction, the
other for edges in Y. The second operation can be divided into many
more chunks, where each chunk is either a set of sections in Z or a set
of lines in Y. The latter is useful when blending a single large
image. Which operations Blendmont does is ordinarily controlled by
two parameters, OldEdgeFunctions and ReadInXcorrs. There are three
common situations:
1) Doing all operations on an initial run of Blendmont:
OldEdgeFunctions 0
ReadInXcorrs 0
2) Computing new edge functions after fixing displacements in Midas:
OldEdgeFunctions 0
ReadInXcorrs 1
3) Just blending images with the existing displacements and edge func-
tions:
OldEdgeFunctions 1
ReadInXcorrs 1
If you enter no options to indicate otherwise, Splitblend will set up
command files to blend images after doing the operations determined by
the values of these options in the command file. However, you can
override what is in the file with the "-r" option to tell it to compute
new edge functions with existing displacements, and with the "-u"
option to tell it just to blend images using existing displacements and
edge functions. You can also use the "-e" option to compute edge func-
tions only, without blending images.
The command file can contain commands before and after the Blendmont
run, but should not contain more than one run of Blendmont.
When X and Y edge functions are computed in parallel, a sync command
file is used to combine the edge correlation displacements from the X
and Y edges into one ".ecd" file.
Blending can be dominated by file input/output, particularly if overlap
zones are small and there are no distortion corrections. If disk
access is slow, there may be little value in running Blendmont in
parallel in such cases.
OPTIONS
Splitblend uses the PIP package for input (see the manual page for
pip). Options can be specified either as command line arguments
(with the -) or one per line in a command file (without the -).
Options can be abbreviated to unique letters; the currently valid
abbreviations for short names are shown in parentheses.
-n Integer
Expected number of machines or processors. The default is 4.
The number of chunks will be 4 times the number of processors,
unless specified with "-t".
-t Integer
The desired number of chunks to set up. The actual number will
be limited by the number of sections when chunks are in Z.
-y Do chunks in Y instead of in Z. Chunks in Y are chosen automat-
ically if there is only one section in Z.
-e Compute edge functions without blending images. This option is
not allowed if the command file specifies to use old edge func-
tions, unless you enter the "-r" option too.
-u Just blend images using existing edge functions and displace-
ments, regardless of the values of the corresponding options in
the command file.
-r Recompute edge functions using existing displacements between
pieces, regardless of the values of the corresponding options in
the command file.
-b Integer
Set the number of boundary pixels saved in separate files to the
given value. The boundary pixels are rewritten to the output
file after all chunks are done.
-help Print help output
-StandardInput
Read parameter entries from standard input
AUTHOR
David Mastronarde
SEE ALSO
blendmont, processchunks, midas
BUGS
Email bug reports to mast at colorado dot edu.
IMOD 5.2.0 splitblend(1)