This is the command pfilt that can be run in the OnWorks free hosting provider using one of our multiple free online workstations such as Ubuntu Online, Fedora Online, Windows online emulator or MAC OS online emulator
PROGRAM:
NAME
pfilt - filter a RADIANCE picture
SYNOPSIS
pfilt [ options ] [ file ]
DESCRIPTION
Pfilt performs anti-aliasing and scaling on a RADIANCE picture. The program makes two
passes on the picture file in order to set the exposure to the correct average value. If
no file is given, the standard input is read.
-x res Set the output x resolution to res. This must be less than or equal to the x
dimension of the target device. If res is given as a slash followed by a real
number, the input resolution is divided by this number to get the output
resolution. By default, the output resolution is the same as the input.
-y res Set the output y resolution to res, similar to the specification of the x
resolution above.
-p rat Set the pixel aspect ratio to rat. Either the x or the y resolution will be
reduced so that the pixels have this ratio for the specified picture. If rat is
zero, then the x and y resolutions will adhere to the given maxima. Zero is the
default.
-c Pixel aspect ratio is being corrected, so do not write PIXASPECT variable to
output file.
-e exp Adjust the exposure. If exp is preceded by a '+' or '-', the exposure is
interpreted in f-stops (ie. the power of two). Otherwise, exp is interpreted as
a straight multiplier. The individual primaries can be changed using -er, -eg
and -eb. Multiple exposure options have a cumulative effect.
-t lamp Color-balance the image as if it were illuminated by fixtures of the given type.
The specification must match a pattern listed in the lamp lookup table (see the
-f option below).
-f lampdat
Use the specified lamp lookup table rather than the default (lamp.tab).
-1 Use only one pass on the file. This allows the exposure to be controlled
absolutely, without any averaging. Note that a single pass is much quicker and
should be used whenever the desired exposure is known and star patterns are not
required.
-2 Use two passes on the input. This is the default.
-b Use box filtering (default). Box filtering averages the input pixels
corresponding to each separate output pixel.
-r rad Use Gaussian filtering with a radius of rad relative to the output pixel size.
This option with a radius around 0.6 and a reduction in image width and height
of 2 or 3 produces the highest quality pictures. A radius greater than 0.7
results in a defocused picture.
-m frac Limit the influence of any given input pixel to frac of any given output pixel.
This option may be used to mitigate the problems associated with inadequate
image sampling, at the expense of a slightly blurred image. The fraction given
should not be less than the output picture dimensions over the input picture
dimensions (x_o*y_o/x_i/y_i), or blurring will occur over the entire image.
This option implies the -r option for Gaussian filtering, which defaults to a
radius of 0.6.
-h lvl Set intensity considered ``hot'' to lvl. This is the level above which areas of
the image will begin to exhibit star diffraction patterns (see below). The
default is 100 watts/sr/m2.
-n N Set the number of points on star patterns to N. A value of zero turns star
patterns off. The default is 0. (Note that two passes are required for star
patterns.)
-s val Set the spread for star patterns to val. This is the value a star pattern will
have at the edge of the image. The default is .0001.
-a Average hot spots as well. By default, the areas of the picture above the hot
level are not used in setting the exposure.
ENVIRONMENT
RAYPATH directories to search for lamp lookup table
Use pfilt online using onworks.net services
