man/man1/ra_xyze.1

.\" RCSid "$Id$"
.TH RA_XYZE 1 5/30/96 RADIANCE
.SH NAME
ra_xyze - convert between RADIANCE RGBE and XYZE formats
.SH SYNOPSIS
.B ra_xyze
[
.B \-r
][
.B "\-e exposure"
][
.B \-c
|
.B \-u
][
.B "\-p xr yr xg yg xb yb xw yw"
]
[
.B input
[
.B output
]
]
.SH DESCRIPTION
.I Ra_xyze
converts between RADIANCE RGBE (red,green,blue,exponent) and XYZE
(CIE X,Y,Z,exponent) formats.
The
.I \-e
option specifies an exposure compensation, which may be given as
a decimal multiplier or in f-stops (powers of two).
By default,
.I ra_xyze
produces a flat XYZE RADIANCE picture file from any type of RADIANCE
input picture.
To override these defaults, the
.I \-c
option may be used to specify run-length encoded output,
or the
.I \-u
option may be used to specify a flat output.
.PP
The
.I \-r
option causes
.I ra_xyze
to produce a run-length encoded RGBE file instead.
The
.I \-p
option may be used to override the standard RADIANCE RGB primary
colors to tailor the image for a particular output device or
representation.
The eight floating-point arguments to this option are the 1931
CIE (x,y) chromaticity coordinates of the three RGB primaries
plus the white point, in that order.
The new primaries will be recorded in the header of the output file,
so that the original information may be fully recovered later.
It is not necessary that the input file by in XYZE format.
Th
.I \-r
option may therefore be used to convert from one RGB primary
representation to another using the
.I \-p
option.
.PP
If the output file is missing, the standard output is used.
If the input file is missing as well, the standard input is used.
.SH NOTES
The CIE standard used is the 1931 2-degree observer, and the
correct output representation relies on the original RADIANCE
input description being defined properly in terms of the standard
RADIANCE RGB primaries, whose CIE (x,y) chromaticity values are
defined in the header file in src/common/color.h.
In this same file is a standard for the luminous efficacy of white
light (WHTEFFICACY), which is used as a conversion between lumens
and watts throughout RADIANCE.
This same factor is applied by
.I ra_xyze
when converting between the radiometric units of the RGBE format
and the photometric units of the XYZE format.
The purpose of this factor is to ensure that the Y component of
the CIE representation is luminance in units of candelas/meter^2.
.PP
Most of the RADIANCE picture filters should work uniformly on either
RGBE or XYZE files, so it is not necessary to convert back to RGBE
format except for conversion or display, in which case the correct
primaries for the chosen output device should be specified with the
.I \-p
option if they are known.
.SH EXAMPLES
To convert RGBE output from
.I rpict(1)
into run-length encoded XYZE format:
.IP "" .2i
rpict [options] scene.oct | ra_xyze -c > scene_xyz.pic
.PP
To prepare a RADIANCE picture for display on a calibrated NTSC monitor:
.IP "" .2i
ra_xyze -r -p .670 .330 .210 .710 .140 .080 .333 .333 stand.pic ntsc.pic
.SH AUTHOR
Greg Ward
.SH BUGS
Any color correction applied to the original image is not removed
or translated by
.I ra_xyze,
and it may result in color shifts in the output.
If color preservation is important and the correction is unwanted,
it is best to remove it with
.I pfilt(1)
using the
.I \-er,
.I \-eg
and
.I \-eb
options first.
(Simply look at the header and apply the reciprocal primaries of all
COLORCORR= lines multiplied together.)
Better still, get the picture before color correction is applied.
.SH "SEE ALSO"
pfilt(1), ra_rgbe(1), rpict(1)
Revision:	1.2
Committed:	Tue Dec 9 15:59:06 2003 UTC (20 years, 5 months ago) by greg
Branch:	MAIN
CVS Tags:	rad3R7P2, rad3R7P1, rad3R6, rad3R6P1
Changes since 1.1:	+1 -1 lines
Log Message:	Fixed RCSid specification
#	User	Rev	Content
1	greg	1.2	.\" RCSid "$Id$"
2	greg	1.1	.TH RA_XYZE 1 5/30/96 RADIANCE
3			.SH NAME
4			ra_xyze - convert between RADIANCE RGBE and XYZE formats
5			.SH SYNOPSIS
6			.B ra_xyze
7			[
8			.B \-r
9			][
10			.B "\-e exposure"
11			][
12			.B \-c
13			\|
14			.B \-u
15			][
16			.B "\-p xr yr xg yg xb yb xw yw"
17			]
18			[
19			.B input
20			[
21			.B output
22			]
23			]
24			.SH DESCRIPTION
25			.I Ra_xyze
26			converts between RADIANCE RGBE (red,green,blue,exponent) and XYZE
27			(CIE X,Y,Z,exponent) formats.
28			The
29			.I \-e
30			option specifies an exposure compensation, which may be given as
31			a decimal multiplier or in f-stops (powers of two).
32			By default,
33			.I ra_xyze
34			produces a flat XYZE RADIANCE picture file from any type of RADIANCE
35			input picture.
36			To override these defaults, the
37			.I \-c
38			option may be used to specify run-length encoded output,
39			or the
40			.I \-u
41			option may be used to specify a flat output.
42			.PP
43			The
44			.I \-r
45			option causes
46			.I ra_xyze
47			to produce a run-length encoded RGBE file instead.
48			The
49			.I \-p
50			option may be used to override the standard RADIANCE RGB primary
51			colors to tailor the image for a particular output device or
52			representation.
53			The eight floating-point arguments to this option are the 1931
54			CIE (x,y) chromaticity coordinates of the three RGB primaries
55			plus the white point, in that order.
56			The new primaries will be recorded in the header of the output file,
57			so that the original information may be fully recovered later.
58			It is not necessary that the input file by in XYZE format.
59			Th
60			.I \-r
61			option may therefore be used to convert from one RGB primary
62			representation to another using the
63			.I \-p
64			option.
65			.PP
66			If the output file is missing, the standard output is used.
67			If the input file is missing as well, the standard input is used.
68			.SH NOTES
69			The CIE standard used is the 1931 2-degree observer, and the
70			correct output representation relies on the original RADIANCE
71			input description being defined properly in terms of the standard
72			RADIANCE RGB primaries, whose CIE (x,y) chromaticity values are
73			defined in the header file in src/common/color.h.
74			In this same file is a standard for the luminous efficacy of white
75			light (WHTEFFICACY), which is used as a conversion between lumens
76			and watts throughout RADIANCE.
77			This same factor is applied by
78			.I ra_xyze
79			when converting between the radiometric units of the RGBE format
80			and the photometric units of the XYZE format.
81			The purpose of this factor is to ensure that the Y component of
82			the CIE representation is luminance in units of candelas/meter^2.
83			.PP
84			Most of the RADIANCE picture filters should work uniformly on either
85			RGBE or XYZE files, so it is not necessary to convert back to RGBE
86			format except for conversion or display, in which case the correct
87			primaries for the chosen output device should be specified with the
88			.I \-p
89			option if they are known.
90			.SH EXAMPLES
91			To convert RGBE output from
92			.I rpict(1)
93			into run-length encoded XYZE format:
94			.IP "" .2i
95			rpict [options] scene.oct \| ra_xyze -c > scene_xyz.pic
96			.PP
97			To prepare a RADIANCE picture for display on a calibrated NTSC monitor:
98			.IP "" .2i
99			ra_xyze -r -p .670 .330 .210 .710 .140 .080 .333 .333 stand.pic ntsc.pic
100			.SH AUTHOR
101			Greg Ward
102			.SH BUGS
103			Any color correction applied to the original image is not removed
104			or translated by
105			.I ra_xyze,
106			and it may result in color shifts in the output.
107			If color preservation is important and the correction is unwanted,
108			it is best to remove it with
109			.I pfilt(1)
110			using the
111			.I \-er,
112			.I \-eg
113			and
114			.I \-eb
115			options first.
116			(Simply look at the header and apply the reciprocal primaries of all
117			COLORCORR= lines multiplied together.)
118			Better still, get the picture before color correction is applied.
119			.SH "SEE ALSO"
120			pfilt(1), ra_rgbe(1), rpict(1)