Table of Contents
pfilt - filter a RADIANCE picture
pfilt [ options ] [ file ]
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.
- 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
- -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).
- 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
- Use two passes on the input. This is the default.
- 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 1 and a reduction in image
width and height of 2 or 3 produces the highest
quality pictures. A radius greater than 1 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 exceed 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 1.
- -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.
- -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.
- Average hot spots as well. By default, the areas
of the picture above the hot level are not used in
setting the exposure.
- directories to search for lamp lookup table
getinfo(1), ies2rad(1), pcompos(1), pflip(1), pinterp(1),
pvalue(1), protate(1), rad(1), rpict(1), ximage(1)
Header and Footer
PFILT(1) RADIANCE (11/15/93) PFILT(1)
Page 1 (printed 7/17/96)
Table of Contents