---
name: "jpeghotp"
section: "1"
platform: "linux"
package: "jpegpixi"
version: "1.1.1-5"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/jpeghotp"
---

# jpeghotp(1)

find hot or dead pixels in otherwise black or white JPEG images

## NAME

jpeghotp - find hot or dead pixels in otherwise black or white JPEG images

## SYNOPSIS

**jpeghotp** \[*OPTION*\]... *JPEG-FILE* \[*PIXEL-BLOCKS-FILE*\]

## DESCRIPTION

Jpeghotp automatically finds hot pixels in an otherwise black JPEG image (default) or dead pixels in an otherwise white JPEG image (if the **--invert** option is specified). The output is suitable as a pixel block specification file for the [**jpegpixi**(1)](/jpegpixi/1.md) program. A typical application is to process an image taken with a digital camera with CCD defects.

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.

*JPEG-FILE* is the filename of the JPEG image to read. It can be **-**, which refers to standard input.

*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.

## OPTIONS

- **-t** *THRESHOLD*, **--threshold**=*THRESHOLD*

  Specify the threshold between noise and signal. Pixel luminosities below the threshold are considered CCD noise, luminosities above are considered hot pixels. *THRESHOLD* must be a number between 0 and 100 followed by a percent character (**%**). The default is **10%**.

- **-i**, **--invert**

  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.

- **-c**, **--comments**

  Output comments with the luminosities of the hot (or dead) pixel blocks. This can be helpful in hand tuning the pixel blocks file.

- **--help**

  Display a short help text and exit immediately.

- **--version**

  Display version information and exit immediately.

## BUGS

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

## COPYRIGHT

Copyright © 2003, 2004, 2005 Martin Dickopp

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.

## SEE ALSO

[**jpegpixi**(1)](/jpegpixi/1.md)

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