man/man1/pfilt.1

.\" RCSid "$Id"
.TH PFILT 1 11/8/96 RADIANCE
.SH NAME
pfilt - filter a RADIANCE picture
.SH SYNOPSIS
.B pfilt
[
.B options
]
[
.B file
]
.SH DESCRIPTION
.I 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
.I file
is given, the standard input is read.
.TP 10n
.BI -x \ res
Set the output x resolution to
.I res.
This must be less than or equal to the x dimension
of the target device.
If
.I 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.
.TP
.BI -y \ res
Set the output y resolution to
.I res,
similar to the specification of the x resolution above.
.TP
.BI -p \ rat
Set the pixel aspect ratio to
.I rat.
Either the x or the y resolution will be reduced so that the pixels have
this ratio for the specified picture.
If
.I rat
is zero, then the x and y resolutions will adhere to the given maxima.
Zero is the default.
.TP
.BI -c
Pixel aspect ratio is being corrected, so do not write PIXASPECT
variable to output file.
.TP
.BI -e \ exp
Adjust the exposure.
If
.I exp
is preceded by a '+' or '-', the exposure is interpreted in f-stops
(ie. the power of two).
Otherwise,
.I exp
is interpreted as a straight multiplier.
The individual primaries can be changed using
.I \-er,
.I \-eg
and
.I \-eb.
Multiple exposure options have a cumulative effect.
.TP
.BR -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).
.TP
.BR -f \ lampdat
Use the specified lamp lookup table rather than the default (lamp.tab).
.TP
.BR \-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.
.TP
.BR \-2
Use two passes on the input.
This is the default.
.TP
.BR \-b
Use box filtering (default).
Box filtering averages the input pixels corresponding
to each separate output pixel.
.TP
.BI -r \ rad
Use Gaussian filtering with a radius of
.I 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.
.TP
.BI -m \ frac
Limit the influence of any given input pixel to
.I 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
.I \-r
option for Gaussian filtering, which defaults to a radius of 0.6.
.TP
.BI -h \ lvl
Set intensity considered ``hot'' to
.I 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.
.TP
.BI -n \ N
Set the number of points on star patterns to
.I N.
A value of zero turns star patterns off.
The default is 0.
(Note that two passes are required for star patterns.)\0
.TP
.BI -s \ val
Set the spread for star patterns to
.I val.
This is the value a star pattern will have at the
edge of the image.
The default is .0001.
.TP
.BR \-a
Average hot spots as well.
By default, the areas of the picture above the hot level
are not used in setting the exposure.
.SH ENVIRONMENT
RAYPATH         directories to search for lamp lookup table
.SH FILES
/usr/tmp/rt??????
.SH AUTHOR
Greg Ward
.SH "SEE ALSO"
getinfo(1), ies2rad(1), pcompos(1), pflip(1), pinterp(1),
pvalue(1), protate(1), rad(1), rpict(1), ximage(1)
Revision:	1.1
Committed:	Tue Mar 11 19:20:21 2003 UTC (22 years, 2 months ago) by greg
Branch:	MAIN
CVS Tags:	rad3R5
Log Message:	Added documentation to repository
#	Content
1	.\" RCSid "$Id"
2	.TH PFILT 1 11/8/96 RADIANCE
3	.SH NAME
4	pfilt - filter a RADIANCE picture
5	.SH SYNOPSIS
6	.B pfilt
7	[
8	.B options
9	]
10	[
11	.B file
12	]
13	.SH DESCRIPTION
14	.I Pfilt
15	performs anti-aliasing and scaling on a RADIANCE picture.
16	The program makes two passes on the picture file in order to
17	set the exposure to the correct average value.
18	If no
19	.I file
20	is given, the standard input is read.
21	.TP 10n
22	.BI -x \ res
23	Set the output x resolution to
24	.I res.
25	This must be less than or equal to the x dimension
26	of the target device.
27	If
28	.I res
29	is given as a slash followed by a real number, the input resolution
30	is divided by this number to get the output resolution.
31	By default, the output resolution is the same as the input.
32	.TP
33	.BI -y \ res
34	Set the output y resolution to
35	.I res,
36	similar to the specification of the x resolution above.
37	.TP
38	.BI -p \ rat
39	Set the pixel aspect ratio to
40	.I rat.
41	Either the x or the y resolution will be reduced so that the pixels have
42	this ratio for the specified picture.
43	If
44	.I rat
45	is zero, then the x and y resolutions will adhere to the given maxima.
46	Zero is the default.
47	.TP
48	.BI -c
49	Pixel aspect ratio is being corrected, so do not write PIXASPECT
50	variable to output file.
51	.TP
52	.BI -e \ exp
53	Adjust the exposure.
54	If
55	.I exp
56	is preceded by a '+' or '-', the exposure is interpreted in f-stops
57	(ie. the power of two).
58	Otherwise,
59	.I exp
60	is interpreted as a straight multiplier.
61	The individual primaries can be changed using
62	.I \-er,
63	.I \-eg
64	and
65	.I \-eb.
66	Multiple exposure options have a cumulative effect.
67	.TP
68	.BR -t \ lamp
69	Color-balance the image as if it were illuminated by fixtures of
70	the given type.
71	The specification must match a pattern listed in the lamp
72	lookup table (see the -f option below).
73	.TP
74	.BR -f \ lampdat
75	Use the specified lamp lookup table rather than the default (lamp.tab).
76	.TP
77	.BR \-1
78	Use only one pass on the file.
79	This allows the exposure to be controlled absolutely, without
80	any averaging.
81	Note that a single pass is much quicker and should be used whenever
82	the desired exposure is known and star patterns are not required.
83	.TP
84	.BR \-2
85	Use two passes on the input.
86	This is the default.
87	.TP
88	.BR \-b
89	Use box filtering (default).
90	Box filtering averages the input pixels corresponding
91	to each separate output pixel.
92	.TP
93	.BI -r \ rad
94	Use Gaussian filtering with a radius of
95	.I rad
96	relative to the output pixel size.
97	This option with a radius around 0.6 and a reduction in image width and
98	height of 2 or 3 produces the highest quality pictures.
99	A radius greater than 0.7 results in a defocused picture.
100	.TP
101	.BI -m \ frac
102	Limit the influence of any given input pixel to
103	.I frac
104	of any given output pixel.
105	This option may be used to mitigate the problems associated with
106	inadequate image sampling, at the expense of a slightly blurred
107	image.
108	The fraction given should not exceed the output picture dimensions
109	over the input picture dimensions (x_o*y_o/x_i/y_i), or blurring
110	will occur over the entire image.
111	This option implies the
112	.I \-r
113	option for Gaussian filtering, which defaults to a radius of 0.6.
114	.TP
115	.BI -h \ lvl
116	Set intensity considered ``hot'' to
117	.I lvl.
118	This is the level above which areas of the image will begin
119	to exhibit star diffraction patterns (see below).
120	The default is 100 watts/sr/m2.
121	.TP
122	.BI -n \ N
123	Set the number of points on star patterns to
124	.I N.
125	A value of zero turns star patterns off.
126	The default is 0.
127	(Note that two passes are required for star patterns.)\0
128	.TP
129	.BI -s \ val
130	Set the spread for star patterns to
131	.I val.
132	This is the value a star pattern will have at the
133	edge of the image.
134	The default is .0001.
135	.TP
136	.BR \-a
137	Average hot spots as well.
138	By default, the areas of the picture above the hot level
139	are not used in setting the exposure.
140	.SH ENVIRONMENT
141	RAYPATH directories to search for lamp lookup table
142	.SH FILES
143	/usr/tmp/rt??????
144	.SH AUTHOR
145	Greg Ward
146	.SH "SEE ALSO"
147	getinfo(1), ies2rad(1), pcompos(1), pflip(1), pinterp(1),
148	pvalue(1), protate(1), rad(1), rpict(1), ximage(1)