.\" This file is part of jpegpixi, a program to interpolate pixels in
.\" JFIF image files.
.\" Copyright (C) 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 JPEGHOTP 1 18-Apr-2005 "jpegpixi 1.1.1" "User Commands"
.SH NAME
jpeghotp \- find hot or dead pixels in otherwise black or white JPEG images
.SH SYNOPSIS
.B jpeghotp
.RI [ OPTION ]...\&
.I JPEG-FILE
.RI [ PIXEL-BLOCKS-FILE ]
.SH DESCRIPTION
Jpeghotp automatically finds hot pixels in an otherwise black JPEG image
(default) or dead pixels in an otherwise white JPEG image (if the
.B \-\-invert
option is specified). The output is suitable as a pixel block
specification file for the
.BR jpegpixi (1)
program. A typical application is to process an image taken with a digital
camera with CCD defects.
.PP
To obtain a black image, take a picture in total darkness or with
covered lens. To obtain a while image, take an overexposed picture of a
well-lit piece of white paper.
.PP
.I JPEG-FILE
is the filename of the JPEG image to read. It can be
.BR \- ,
which refers to standard input.
.PP
.I PIXEL-BLOCKS-FILE
is the name of the file to write the coordinates and sizes of the hot
(or dead) pixel blocks to. If it is omitted, the coordinates and sizes
are written to standard output.
.SH OPTIONS
.IP "\fB\-t\fR \fITHRESHOLD\fR, \fB\-\-threshold\fR=\fITHRESHOLD\fR"
Specify the threshold between noise and signal. Pixel luminosities below
the threshold are considered CCD noise, luminosities above are considered
hot pixels.
.I THRESHOLD
must be a number between 0 and 100 followed by a percent character
.RB ( % ).
The default is
.BR 10% .
.IP "\fB\-i\fr, \fB\-\-invert\fR"
Invert the image. If this option is specified, dead pixels in an
otherwise white image instead of hot pixels in an otherwise black image
are found.
.IP "\fB\-c\fR, \fB\-\-comments\fR"
Output comments with the luminosities of the hot (or dead) pixel blocks.
This can be helpful in hand tuning the pixel blocks file.
.IP "\fB\-\-help\fR"
Display a short help text and exit immediately.
.IP "\fB\-\-version\fR"
Display version information and exit immediately.
.SH BUGS
Please report bugs to <martin\-jpegpixi@zero\-based.org>.
.SH COPYRIGHT
Copyright \(co 2003, 2004, 2005 Martin Dickopp
.PP
Jpeghotp 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 jpegpixi (1)
.PP
The jpegpixi homepage:
http://www.zero\-based.org/software/jpegpixi/
.
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