| |
pfilt (1)
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. |
|
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. |
|
Set the output y resolution to res, similar to the
specification of the x resolution above. |
|
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. |
|
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. |
|
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). |
|
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. |
|
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. |
|
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. |
|
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. |
|
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.) |
|
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 |
FILES
AUTHOR
SEE ALSO
|
