.\" This file is part of jpegpixi, a program to interpolate pixels in
.\" JFIF image files.
.\" Copyright (C) 2002, 2003, 2004, 2005 Martin Dickopp
.
.\" Jpegpixi is free software; you can redistribute it and/or modify
.\" it under the terms of the GNU General Public License as published
.\" by the Free Software Foundation; either version 2 of the License,
.\" or (at your option) any later version.
.
.\" Jpegpixi is distributed in the hope that it will be useful,
.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
.\" GNU General Public License for more details.
.
.\" You should have received a copy of the GNU General Public License
.\" along with jpegpixi; if not, write to the Free Software
.\" Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301,
.\" USA.
.
.TH JPEGPIXI 1 20-Nov-2005 "jpegpixi 1.1.1" "User Commands"
.SH NAME
jpegpixi \- interpolate pixels in JFIF (JPEG) image files
.SH SYNOPSIS
.B jpegpixi
.RI [ OPTION ]...\&
.I SOURCE DEST
[[\fID\fR:]\fIX\fR,\fIY\fR[,\fIS\fR]|[,\fISX\fR,\fISY\fR]]...
.SH 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.
.PP
.I SOURCE
and
.I DEST
are the filenames of the source file and the destination file,
respectively. In both cases,
.B \-
can be used, which refers to standard input or standard output.
.PP
The destination filename is followed by any number of pixel or pixel block
specifications. It starts with an optional direction specifier
.RI ( D ),
which can be
.B 2
for 2-dimensional interpolation (the default),
.B V
or
.B v
for 1-dimensional vertical interpolation (e.g.\ to remove horizontal
stripes), or
.B H
or
.B h
for 1-dimensional horizontal interpolation.
.IR X , Y
are the coordinates of the pixel or the upper-left corner of the pixel
block.
.I S
is the size of the pixel block (1 by default). Alternatively,
separate sizes can be specified for the width
.RI ( SX )
and the height
.RI ( SY ).
.PP
All numbers
.RI ( X ,
.IR Y ,
.IR S ,
.IR SX ,
.IR SY )
can be expressed as absolute coordinates/sizes or percentages of the image
size. If a number is followed by a percent character
.RB ( % ),
it is interpreted as a percentage, otherwise as an absolute number.
.SH OPTIONS
.IP "\fB\-f\fR \fIFILE\fR, \fB\-\-blocks\-file\fR=\fIFILE\fR"
Read pixel block specifications from file
.I FILE
in addition to the command line. The file should contain one specification
([\fID\fR:]\fIX\fR,\fIY\fR[,\fIS\fR]|[,\fISX\fR,\fISY\fR]) per line. Empty
lines are ignored. The file may also contain comments, which start with an
octothorpe
.RB ( # )
and extend to the end of the line.
.IP "\fB\-m\fR \fIMETHOD\fR, \fB\-\-method\fR=\fIMETHOD\fR"
Use interpolation method
.I METHOD
(default:
.BR linear ).
See section INTERPOLATION METHODS below.
.IP "\fB\-v\fR, \fB\-\-verbose\fR"
Display the coordinates and size of each pixel block that is
interpolated.
.IP "\fB\-i\fR, \fB\-\-info\fR"
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.
.IP "\fB\-s\fR, \fB\-\-strip\fR"
Do not copy comment and extra markers from the source to the
destination file. This strips preview images, EXIF data, and similar
information.
.IP "\fB\-\-help\fR"
Display a short help text and exit immediately.
.IP "\fB\-\-version\fR"
Display version information and exit immediately.
.SH "INTERPOLATION METHODS"
.IP "\fB0\fR, \fBav\fR, \fBaverage\fR"
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.
.IP "\fB1\fR, \fBli\fR, \fBlinear\fR"
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.
.IP "\fB2\fR, \fBqu\fR, \fBquadratic\fR"
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.
.IP "\fB3\fR, \fBcu\fR, \fBcubic\fR"
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.
.SH BUGS
Please report bugs to <martin\-jpegpixi@zero\-based.org>.
.SH COPYRIGHT
Copyright \(co 2002, 2003, 2004, 2005 Martin Dickopp
.PP
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.
.SH "SEE ALSO"
.BR jpeghotp (1)
.PP
The jpegpixi homepage:
http://www.zero\-based.org/software/jpegpixi/
.
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