man/man1/pcomb.1

.\" RCSid "$Id: pcomb.1,v 1.10 2018/02/05 20:07:17 greg Exp $"
.TH PCOMB 1 8/31/96 RADIANCE
.SH NAME
pcomb - combine RADIANCE pictures
.SH SYNOPSIS
.B pcomb
[
.B -h
][
.B -w
][
.B "\-x xres"
][
.B "\-y yres"
][
.B "\-f file"
][
.B "\-e expr"
]
[
[
.B -o
][
.B "\-s factor"
][
.B "\-c r g b"
]
.B "input .."
]
.SH DESCRIPTION
.I Pcomb
combines equal-sized RADIANCE pictures and sends the result to the
standard output.
By default, the result is just a linear combination of
the input pictures multiplied by
.I \-s
and
.I \-c
coefficients,
but an arbitrary mapping can be assigned with the
.I \-e
and
.I \-f
options.
The variable and function definitions in each
.I \-f source
file are read and compiled from the RADIANCE library where it is found.
Negative coefficients and functions are allowed, and
.I pcomb
will produce color values of zero where they would be negative.
.PP
The variables
.I ro,
.I go
and
.I bo
specify the red, green and blue output values, respectively.
Alternatively, the single variable
.I lo
can be used to specify a brightness value for black and white output.
The predefined functions
.I ri(n),
.I gi(n)
and
.I bi(n)
give the red, green and blue input values for
picture
.I n.
To access a pixel that is nearby the current one, these functions
also accept optional x and y offsets.
For example,
.I ri(3,-2,1)
would return the red component of the pixel from picture 3
that is left 2 and up 1 from the current position.
Although x offsets may be as large as width of the picture,
y offsets are limited to a small window (+/- 32 pixels) due to efficiency
considerations.
However, it is not usually necessary to worry about this problem --
if the requested offset is not available, the next best pixel is
returned instead.
.PP
For additional convenience, the function
.I li(n)
is defined as the input brightness for picture
.I n.
This function also accepts x and y offsets.
.PP
The constant
.I nfiles
gives the number of input files present,
and
.I WE
gives the white efficacy (lumens/brightness) for pixel values,
which may be used with the
.I \-o
option or the le(n) values to convert to absolute
photometric units (see below).
The variables
.I x
and
.I y
give the current output pixel location for use in
spatially dependent functions, the constants
.I xmax
and
.I ymax
give the input resolution, and the constants
.I xres
and 
.I yres
give the output resolution (usually the same, but see below).
The constant functions
.I "re(n), ge(n), be(n),"
and
.I le(n)
give the exposure values for picture
.I n,
and
.I pa(n)
gives the corresponding pixel aspect ratio.
Finally, for pictures with stored view parameters,
the functions
.I "Ox(n), Oy(n)"
and
.I Oz(n)
return the ray origin in world coordinates for the current pixel
in picture
.I n,
and
.I "Dx(n), Dy(n)"
and
.I Dz(n)
return the normalized ray direction.
In addition, the function
.I T(n)
returns the distance from the origin to the aft clipping plane
(or zero if there is no aft plane), and the function
.I S(n)
returns the solid angle of the current pixel in steradians
(always zero for parallel views).
If the current pixel is outside the view region,
.I T(n)
will return a negative value, and
.I S(n)
will return zero.
The first input picture with a view is assumed to correspond to the
view of the output picture, which is written into the header.
.PP
The
.I \-h
option may be used to reduce the information header size, which
can grow disproportionately after multiple runs of
.I pcomb
and/or
.I pcompos(1).
The
.I \-w
option can be used to suppress warning messages about invalid
calculations.
The
.I \-o
option indicates that original pixel values are to be used for the next
picture, undoing any previous exposure changes or color correction.
.PP
The
.I \-x
and
.I \-y
options can be used to specify the desired output resolution,
.I xres
and
.I yres,
and can be expressions involving other constants such as
.I xmax
and
.I ymax.
The constants
.I xres
and
.I yres
may also be specified in a file or expression.
The default output resolution is the same as the input resolution.
.PP
The
.I \-x
and
.I \-y
options must be present if there are no input files, when
the definitions of
.I ro,
.I go
and
.I bo
will be used to compute each output pixel.
This is useful for producing simple test pictures for various
purposes.
(Theoretically, one could write a complete renderer using just the
functional language...)
.PP
The standard input can be specified with a hyphen ('-').
A command that produces a RADIANCE picture can be given in place of a file 
by preceeding it with an exclamation point ('!').
.SH EXAMPLES
To produce a picture showing the difference between pic1 and pic2:
.IP "" .2i
pcomb \-e 'ro=ri(1)\-ri(2);go=gi(1)\-gi(2);bo=bi(1)\-bi(2)' pic1 pic2 > diff
.PP
Or, more efficiently:
.IP "" .2i
pcomb pic1 \-s \-1 pic2 > diff
.PP
To precompute the gamma correction for a picture:
.IP "" .2i
pcomb \-e 'ro=ri(1)^.4;go=gi(1)^.4;bo=bi(1)^.4' inp.hdr > gam.hdr
.PP
To perform some special filtering:
.IP "" .2i
pcomb \-f myfilt.cal \-x xmax/2 \-y ymax/2 input.hdr > filtered.hdr
.PP
To make a picture of a dot:
.IP "" .2i
pcomb \-x 100 \-y 100 \-e 'ro=b;go=b;bo=b;b=if((x-50)^2+(y-50)^2\-25^2,0,1)' > dot
.SH ENVIRONMENT
RAYPATH         the directories to check for auxiliary files.
.SH AUTHOR
Greg Ward
.SH "SEE ALSO"
getinfo(1), icalc(1), pcompos(1), pfilt(1), rpict(1)
Revision:	1.11
Committed:	Fri May 4 23:56:49 2018 UTC (6 years, 1 month ago) by greg
Branch:	MAIN
CVS Tags:	rad5R2, rad5R3
Changes since 1.10:	+6 -1 lines
Log Message:	Added search to -f for genrev, gensurf, genworm, bsdf2klems, bsdf2ttree, & pcomb
#	Content
1	.\" RCSid "$Id: pcomb.1,v 1.10 2018/02/05 20:07:17 greg Exp $"
2	.TH PCOMB 1 8/31/96 RADIANCE
3	.SH NAME
4	pcomb - combine RADIANCE pictures
5	.SH SYNOPSIS
6	.B pcomb
7	[
8	.B -h
9	][
10	.B -w
11	][
12	.B "\-x xres"
13	][
14	.B "\-y yres"
15	][
16	.B "\-f file"
17	][
18	.B "\-e expr"
19	]
20	[
21	[
22	.B -o
23	][
24	.B "\-s factor"
25	][
26	.B "\-c r g b"
27	]
28	.B "input .."
29	]
30	.SH DESCRIPTION
31	.I Pcomb
32	combines equal-sized RADIANCE pictures and sends the result to the
33	standard output.
34	By default, the result is just a linear combination of
35	the input pictures multiplied by
36	.I \-s
37	and
38	.I \-c
39	coefficients,
40	but an arbitrary mapping can be assigned with the
41	.I \-e
42	and
43	.I \-f
44	options.
45	The variable and function definitions in each
46	.I \-f source
47	file are read and compiled from the RADIANCE library where it is found.
48	Negative coefficients and functions are allowed, and
49	.I pcomb
50	will produce color values of zero where they would be negative.
51	.PP
52	The variables
53	.I ro,
54	.I go
55	and
56	.I bo
57	specify the red, green and blue output values, respectively.
58	Alternatively, the single variable
59	.I lo
60	can be used to specify a brightness value for black and white output.
61	The predefined functions
62	.I ri(n),
63	.I gi(n)
64	and
65	.I bi(n)
66	give the red, green and blue input values for
67	picture
68	.I n.
69	To access a pixel that is nearby the current one, these functions
70	also accept optional x and y offsets.
71	For example,
72	.I ri(3,-2,1)
73	would return the red component of the pixel from picture 3
74	that is left 2 and up 1 from the current position.
75	Although x offsets may be as large as width of the picture,
76	y offsets are limited to a small window (+/- 32 pixels) due to efficiency
77	considerations.
78	However, it is not usually necessary to worry about this problem --
79	if the requested offset is not available, the next best pixel is
80	returned instead.
81	.PP
82	For additional convenience, the function
83	.I li(n)
84	is defined as the input brightness for picture
85	.I n.
86	This function also accepts x and y offsets.
87	.PP
88	The constant
89	.I nfiles
90	gives the number of input files present,
91	and
92	.I WE
93	gives the white efficacy (lumens/brightness) for pixel values,
94	which may be used with the
95	.I \-o
96	option or the le(n) values to convert to absolute
97	photometric units (see below).
98	The variables
99	.I x
100	and
101	.I y
102	give the current output pixel location for use in
103	spatially dependent functions, the constants
104	.I xmax
105	and
106	.I ymax
107	give the input resolution, and the constants
108	.I xres
109	and
110	.I yres
111	give the output resolution (usually the same, but see below).
112	The constant functions
113	.I "re(n), ge(n), be(n),"
114	and
115	.I le(n)
116	give the exposure values for picture
117	.I n,
118	and
119	.I pa(n)
120	gives the corresponding pixel aspect ratio.
121	Finally, for pictures with stored view parameters,
122	the functions
123	.I "Ox(n), Oy(n)"
124	and
125	.I Oz(n)
126	return the ray origin in world coordinates for the current pixel
127	in picture
128	.I n,
129	and
130	.I "Dx(n), Dy(n)"
131	and
132	.I Dz(n)
133	return the normalized ray direction.
134	In addition, the function
135	.I T(n)
136	returns the distance from the origin to the aft clipping plane
137	(or zero if there is no aft plane), and the function
138	.I S(n)
139	returns the solid angle of the current pixel in steradians
140	(always zero for parallel views).
141	If the current pixel is outside the view region,
142	.I T(n)
143	will return a negative value, and
144	.I S(n)
145	will return zero.
146	The first input picture with a view is assumed to correspond to the
147	view of the output picture, which is written into the header.
148	.PP
149	The
150	.I \-h
151	option may be used to reduce the information header size, which
152	can grow disproportionately after multiple runs of
153	.I pcomb
154	and/or
155	.I pcompos(1).
156	The
157	.I \-w
158	option can be used to suppress warning messages about invalid
159	calculations.
160	The
161	.I \-o
162	option indicates that original pixel values are to be used for the next
163	picture, undoing any previous exposure changes or color correction.
164	.PP
165	The
166	.I \-x
167	and
168	.I \-y
169	options can be used to specify the desired output resolution,
170	.I xres
171	and
172	.I yres,
173	and can be expressions involving other constants such as
174	.I xmax
175	and
176	.I ymax.
177	The constants
178	.I xres
179	and
180	.I yres
181	may also be specified in a file or expression.
182	The default output resolution is the same as the input resolution.
183	.PP
184	The
185	.I \-x
186	and
187	.I \-y
188	options must be present if there are no input files, when
189	the definitions of
190	.I ro,
191	.I go
192	and
193	.I bo
194	will be used to compute each output pixel.
195	This is useful for producing simple test pictures for various
196	purposes.
197	(Theoretically, one could write a complete renderer using just the
198	functional language...)
199	.PP
200	The standard input can be specified with a hyphen ('-').
201	A command that produces a RADIANCE picture can be given in place of a file
202	by preceeding it with an exclamation point ('!').
203	.SH EXAMPLES
204	To produce a picture showing the difference between pic1 and pic2:
205	.IP "" .2i
206	pcomb \-e 'ro=ri(1)\-ri(2);go=gi(1)\-gi(2);bo=bi(1)\-bi(2)' pic1 pic2 > diff
207	.PP
208	Or, more efficiently:
209	.IP "" .2i
210	pcomb pic1 \-s \-1 pic2 > diff
211	.PP
212	To precompute the gamma correction for a picture:
213	.IP "" .2i
214	pcomb \-e 'ro=ri(1)^.4;go=gi(1)^.4;bo=bi(1)^.4' inp.hdr > gam.hdr
215	.PP
216	To perform some special filtering:
217	.IP "" .2i
218	pcomb \-f myfilt.cal \-x xmax/2 \-y ymax/2 input.hdr > filtered.hdr
219	.PP
220	To make a picture of a dot:
221	.IP "" .2i
222	pcomb \-x 100 \-y 100 \-e 'ro=b;go=b;bo=b;b=if((x-50)^2+(y-50)^2\-25^2,0,1)' > dot
223	.SH ENVIRONMENT
224	RAYPATH the directories to check for auxiliary files.
225	.SH AUTHOR
226	Greg Ward
227	.SH "SEE ALSO"
228	getinfo(1), icalc(1), pcompos(1), pfilt(1), rpict(1)