jpegpixi - Online in the Cloud

PROGRAM:

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.

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