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NAME

       jpegpixi - interpolate pixels in JFIF (JPEG) image files

SYNOPSIS

       jpegpixi [OPTION]... SOURCE DEST [[D:]X,Y[,S]|[,SX,SY]]...

DESCRIPTION

       Jpegpixi  interpolates  pixels  or  pixel  blocks  in JFIF images files
       (commonly referred to as "JPEG images").  This  is  useful  to  correct
       images  from  a  digital camera with CCD defects. Only DCT blocks which
       contain pixels to be interpolated are decoded and re-encoded,  and  the
       re-encoding  is  performed  with exactly the same parameters with which
       the image has originally been encoded. Therefore, the image quality  is
       preserved as much as possible.

       SOURCE  and  DEST  are  the  filenames  of  the  source  file  and  the
       destination file, respectively. In both cases, -  can  be  used,  which
       refers to standard input or standard output.

       The  destination  filename  is followed by any number of pixel or pixel
       block specifications. It starts with an  optional  direction  specifier
       (D), which can be 2 for 2-dimensional interpolation (the default), V or
       v for 1-dimensional vertical interpolation (e.g. to  remove  horizontal
       stripes),  or  H  or h for 1-dimensional horizontal interpolation.  X,Y
       are the coordinates of the pixel or the upper-left corner of the  pixel
       block.  S is the size of the pixel block (1 by default). Alternatively,
       separate sizes can be specified for the width (SX) and the height (SY).

       All   numbers   (X,  Y,  S,  SX,  SY)  can  be  expressed  as  absolute
       coordinates/sizes or percentages of the image  size.  If  a  number  is
       followed by a percent character (%), it is interpreted as a percentage,
       otherwise as an absolute number.

OPTIONS

       -f FILE, --blocks-file=FILE
              Read pixel block specifications from file FILE  in  addition  to
              the  command  line.  The  file  should contain one specification
              ([D:]X,Y[,S]|[,SX,SY]) per line. Empty lines  are  ignored.  The
              file  may  also contain comments, which start with an octothorpe
              (#) and extend to the end of the line.

       -m METHOD, --method=METHOD
              Use interpolation method METHOD (default: linear).  See  section
              INTERPOLATION METHODS below.

       -v, --verbose
              Display  the  coordinates  and  size of each pixel block that is
              interpolated.

       -i, --info
              Display information about the image, such as  the  size  of  the
              image, the colorspace in which it is encoded, and sampling rates
              for the different components.

       -s, --strip
              Do not copy comment and extra markers from  the  source  to  the
              destination  file.  This  strips  preview images, EXIF data, and
              similar information.

       --help Display a short help text and exit immediately.

       --version
              Display version information and exit immediately.

INTERPOLATION METHODS

       0, av, average
              The pixels  adjacent  to  the  pixel  block  are  averaged.  The
              resulting  color  is  assigned  to  all pixels in the block. For
              1-dimensional interpolation, this is  done  separately  for  one
              pixel wide, horizontal or vertical stripes.

       1, li, linear
              The  pixels  which have a distance of 1 from the pixel block are
              used to calculate a bilinear surface  (2-dim),  or  a  group  of
              linear  curves  (1-dim),  which is then used to assign colors to
              the pixels in the block.

       2, qu, quadratic
              The pixels which have a distance of 2 or  less  from  the  pixel
              block  are used to calculate a biquadratic surface (2-dim), or a
              group of quadratic curves (1-dim), which is then used to  assign
              colors to the pixels in the block.

       3, cu, cubic
              The  pixels  which  have  a distance of 3 or less from the pixel
              block are used to calculate a  bicubic  surface  (2-dim),  or  a
              group  of  cubic  curves  (1-dim),  which is then used to assign
              colors to the pixels in the block.

BUGS

       Please report bugs to <martin-jpegpixi@zero-based.org>.

COPYRIGHT

       Copyright © 2002, 2003, 2004, 2005 Martin Dickopp

       Jpegpixi is free software; it may be copied and/or modified  under  the
       terms  of  the GNU General Public License version 2 or (at your option)
       any later version. There is NO warranty; not even  for  MERCHANTABILITY
       or FITNESS FOR A PARTICULAR PURPOSE.

SEE ALSO

       jpeghotp(1)

       The jpegpixi homepage: http://www.zero-based.org/software/jpegpixi/