Pamflip User Manual(0) Pamflip User Manual(0)NAMEpamflip - flip or rotate a PAM or PNM image
SYNOPSISpamflip { -leftright | -lr | -topbottom | -tb | -transpose | -xy |
-rotate90 | -r90 | -cw | -rotate270 | -r270 | -ccw | -rotate180 | -r180
-null | -xform=xform1,xform2... } [-memsize=mebibytes] [-page‐
size=bytes] [pamfile]
All options can be abbreviated to their shortest unique prefix. You
may use two hyphens instead of one to designate an option. You may use
either white space or an equals sign between an option name and its
value.
DESCRIPTION
This program is part of Netpbm(1).
pamflip flips a PAM or PNM image top for bottom or left for right, or
transposes it horizontal for vertical, or rotates it 1, 2, or 3 quarter
turns.
To rotate at other angles, use pnmrotate. It is much slower, though.
The input image is pamfile, or Standard Input if pamfile is not speci‐
fied.
To flip/rotate a JFIF (JPEG) image losslessly, use jpegtran. jpegtran
is part of the Independent Jpeg Group's compression library package,
not part of Netpbm. The normal Netpbm way to flip a JFIF file would be
to convert it to PNM, use pamflip, and convert back to JFIF. But since
JPEG compression is lossy, the resulting image would have less quality
than the original. jpegtran, on the other hand, can do this particular
transformation directly on the compressed data without loss.
OPTIONS
You must supply exactly one of the following options:
pamflip's predecessor (before Netpbm 10.7 - August 2002) pnmflip did
not have the -xform option and instead allowed you to specify any num‐
ber of the other options, including zero. It applied all the indicated
transformations, in the order given, just like with pamflip's -xform
option. (Reason for the change: this kind of interpretation of options
is inconsistent with the rest of Netpbm and most of the Unix world, and
thus hard to understand and to implement).
-leftright
-lr Flip left for right.
-topbottom
-tb Flip top for bottom.
-transpose
-xy Transpose horizontal for vertical. I.e. make the pixel at (x,y)
be at (y,x).
-rotate90
-r90
-ccw Rotate counterclockwise 90 degrees.
-rotate180
-r180 Rotate 180 degrees.
-rotate270
-r270
-cw Rotate counterclockwise 270 degrees (clockwise 90 degrees)
-null No change. (The purpose of this option is the convenience of
programs that invoke pamflip after computing the kind of trans‐
formation desired, including none at all).
This option was new in Netpbm 10.13 (December 2002).
-xform=xform1,xform2...
Apply all the transforms listed, in order. The valid values for
the transforms are as follows and have the same meanings as the
identically named options above.
· leftright
· topbottom
· transpose
This option was new in Netpbm 10.13 (December 2002).
The following options help pamflip use memory efficiently. Some flip‐
ping operations on very large images can cause pamflip to have a very
large working set, which means if you don't have enough real memory,
the program can page thrash, which means it takes a ridiculous amount
time to run. If your entire image fits in real memory, you don't have
a problem. If you're just flipping top for bottom or left for right,
you don't have a problem. Otherwise, pay attention. If you're inter‐
ested in the details of the thrashing problem and how pamflip
approaches it, you're invited to read a complete explanation in com‐
ments in the source code.
-memsize=mebibytes
mebibytes is the size in mebibytes (aka megabytes) of real mem‐
ory (not virtual) available for pamflip. pamflip does nothing
special to allocate real memory or control it's allocation -- it
gets whatever it gets just by referencing virtual memory nor‐
mally. This is the maximum amount that pamflip can be expected
to end up with by doing that. This is just about impossible for
you to know, of course, but you can estimate. The total real
memory in your system should be a major factor in your estimate.
When you specify -memsize and are doing a row for column type of
transformation, pamflip does the transformation in multiple
passes, each one with a working set size less than the specified
value.
If your estimate is even slightly too large, it's the same as
infinity. If you estimate too small, pamflip will use more
passes than it needs to, and thus will slow down proportional to
the underestimate.
If you do not specify -memsize, pamflip assumes infinite real
memory and does the entire transformation in one pass.
This option did not exist before Netpbm 10.7 (August 2002).
-pagesize=bytes
bytes is the size in bytes of a paging unit -- the amount of
memory that gets paged in or out as an indivisible unit -- in
your system. The default is 4KiB.
This option did not exist before Netpbm 10.7 (August 2002).
Miscellaneous options:
-verbose
This option causes pamflip to issue messages to Standard Error
about its progress.
SEE ALSOpnmrotate(1), pnm(1), jpegtran manual
HISTORYpamflip replaced pnmflip in Netpbm 10.13 (December 2002). pamflip is
backward compatible, but also works on PAM images.
AUTHOR
Copyright (C) 1989 by Jef Poskanzer.
netpbm documentation 18 February 2005 Pamflip User Manual(0)
