pamflip



Pamflip User Manual(0)                                  Pamflip User Manual(0)




NAME

       pamflip - flip or rotate a PAM or PNM image



SYNOPSIS

       pamflip  {  -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 ALSO

       pnmrotate(1), pnm(1), jpegtran manual


HISTORY

       pamflip 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)

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