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Jpegpixi, interpolate pixels in JFIF (JPEG) image files

Jpegpixi’ is short for ‘JPEG Pixel Interpolator’. The intent of the program is to interpolate pixels (single pixels, dots, stripes) in JPEG images. This is useful to correct images from a digital camera with CCD defects. For example, if one pixel is always bright green, this pixel can be interpolated with jpegpixi.

Jpegpixi is unique in that it tries to preserve the quality of the JPEG image as much as possible. Usual graphics programs decode JPEG images when they are loaded, and re-encode them when they are saved, which results in an overall loss of quality. Jpegpixi, on the other hand, only decodes the DCT blocks (typically 8×8, 16×8, or 16×16 pixel areas) which contain pixels to be interpolated, and when it re-encodes them, it uses exactly the same parameters with which the image has originally been encoded. These blocks are therefore only minimally disturbed, and other blocks remain pixel-by-pixel identical to the original image.

Jpegpixi is a command line utility. Its messages and the manual pages are available in four languages:

* English,
* Finnish
* French
* German.

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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.


Download:

To build the program, you need *-> version 6b of the JPEG library by the *-> Independent JPEG Group.

  • Version 1.1.1 (20-Nov-2005, latest release):
    • Source: jpegpixi-1.1.1.tar.gz (152 KB)
    • Digital signature: jpegpixi-1.1.1.tar.gz.sig
    • New in this version:
      • Fixed typo in English jpegpixi manual page.
      • Updated postal address of the Free Software Foundation.
  • Version 1.1.0 (01-Jun-2005):
    • Source: jpegpixi-1.1.0.tar.gz (152 KB)
    • Digital signature: jpegpixi-1.1.0.tar.gz.sig
    • New in this version:
      • From now on, I will sign releases. Information on how to obtain and verify my key is available on the contact information page.
      • In addition to hot pixels in an otherwise black image, the jpeghotp program can now also find dead pixels in an otherwise white image.
      • The programms fail gracefully if the locale cannot be set.

Debian packages are also available.

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About Hugo Repetto

Ubuntu is a Linux distribution that offers an operating system predominantly focused on desktop computers but also provides support for servers. Based on Debian GNU / Linux, Ubuntu focuses on ease of use, freedom in usage restriction, regular releases (every 6 months) and ease of installation.
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