spectro/spec2cie
Summary
Convert spectral .ti3
readings into CIE XYZ or L*a*b* readings. FWA compensation may be
applied.
Usage
spec2cie [options] input.ti3
output.ti3
-v
Verbose mode
-i illum Choose
illuminant
for print/transparency spectral data:
A, C, D50 (def.), D65, F5,
F8, F10 or file.sp
-o
observ
Choose CIE Observer for spectral
data:
1931_2 (def.), 1964_10, S&B
1955_2, 1964_10c, shaw, J&V 1978_2
-f
Use
Fluorescent Whitening Agent compensation
-I illum Override
instrument illuminant
in .ti3 file:
A, C, D50, D65, F5,
F8, F10 or file.sp
(only used in conjunction with -f)
-n
Don't output spectral values
-p
Plot
each values spectrum
input.ti3
Measurement file
output.ti3 Converted
measurement file
Comments
This program takes the spectral data in a .ti3 file, converts them to
XYZ and Lab and fills the XYZ_[XYZ] and LAB_[LAB] columns in the output
.ti3 file with the computed XYZ and Lab values. If the columns
XYZ_[XYZ] and/or LAB_[LAB] are missing in the input file, they are
added to the output file.
All other columns are copied from the input to the output .ti3 file.
If the -f option is used, the
FWA corrected spectral reflectances are written to the output .ti3
file, instead of simply copying the spectral reflectances from the
input .ti3 file. In this case, the XYZ_[XYZ] and LAB_[LAB] values are
computed from the FWA corrected reflectances as well.
The -i flag allows specifying a standard or
custom illumination spectrum, applied to spectral .ti3 data to compute
PCS (Profile Connection Space) tristimulus values. A, D50,
D65, F5, F8, F10 are a selection of
standard illuminant spectrums, with D50 being the default. If a
filename is specified instead, it will be assumed to be an Argyll
specific .sp custom spectrum file.
This only works if spectral data is available. Illuminant details are:
A CIE tungsten
filament lamp 2848K
D50 CIE daylight 5000K
D65 CIE daylight 6500K
F5 CIE Fluorescent
6350K, CRI 72
F8 CIE Fluorescent
5000K, CRI 95
F10 CIE Fluorescent 5000K,
CRI 81
Custom illuminants are most often used when a fluorescent tube base
viewing booth is going to be used to view results. Other
illuminant reference files could be created using a suitable measuring
instrument such as a spectrocam, or an eyeone, although such
instruments do not provide the necessary response down to Ultra Violet
that is needed for accurate operation of Fluorescent Whitening Agent
compensation.
Note that if an illuminant other than D50 is chosen, the resulting ICC
profile will not be standard, and cannot be freely interchanged with
other profiles that that us the standard D50 illuminant. Profiles
should only be linked with other profiles that have the same illuminant
and observer.
The -o flag allows specifying a tristimulus
observer, and is used to compute PCS (Profile Connection Space)
tristimulus values. The following choices are available:
1931_2 selects the standard CIE 1931 2 degree observer
(the default).
1964_10 selects the standard CIE 1964 10 degree observer.
1955_2 selects the Stiles and Birch 1955 2 degree
observer
1964_10c selects a version of the CIE 1964 10 degree
observer adjusted for better compatibility with the 1931 2 degree
observer.
1978_2 selects the Judd and Voss 1978 2 degree observer
shaw selects the Shaw and Fairchild 1997 2 degree
observer
Note that if an observer other than 1931 2 degree is chosen, the
resulting ICC profile will not be standard, and cannot be freely
interchanged with other profiles that that us the standard 1931 2
degree
observer. Profiles should only be linked with other profiles that have
the same illuminant and observer.
The -f flag enables Fluorescent Whitening
Agent compensation. This
allows the effects of different levels of Ultra Violet in the viewing
illuminant from that used by the instrument, be compensated for.
The -I flag allows specifying a an illumination
spectrum for the instrument illuminant, overriding that computed from
the type of instrument (recorded in the .ti3 file). This flag is can
only be used in combination with the -f
flag. If a
filename is specified instead, it will be assumed to be an Argyll
specific .sp custom spectrum file.
Illuminant details are:
A CIE tungsten
filament lamp 2848K
D50 CIE daylight 5000K
D65 CIE daylight 6500K
F5 CIE Fluorescent
6350K, CRI 72
F8 CIE Fluorescent
5000K, CRI 95
F10 CIE Fluorescent 5000K,
CRI 81
The -n flag
disables the output of the spectral values. If just the XYZ and L*a*b*
values are needed, this makes for a smaller, easier to read file.
The -p flag
causes each spectrum to be plotted. If FWA compensation is used, then
the before/after compensation spectrums will be shown.