How do I verify spectral reflection value scale is 0-1.0 or 0-100.0 in CGATS?

[diuming]

Question

I get a spectral(380nm to 730nm) reflection values saved in CGATS file.
according to i1Profiler it can be saved as 0-1.0 or 0-100.0 value scale.
How do i verify the reflection value scale is 0-1.0 or 0-100.0?

If I known the maximum reflection value maybe can resolve this problem. if so.
For example:
The maximum reflection value is 1.5 any value over it denote the value scale is 0-100.0.

Is there a defined reflection maximum value?

Could you give me any advice?

thanks

[KelSolaar]

Hi @diuming,

I lost my access to the standard so I cannot verify if there is a formal indication on how this is meant to be done. I sent an email to ANSI so that they reinstate my download, I will keep you posted if I can find more details!

Cheers,

Thomas

[glenndavis52]

Hi @diuming ,

I don't know about i1Profiler, but programs in the Argyll CMS suite write
CGATS files (with extension .sp) with the keyword SPECTRAL_NORM, e.g.
SPECTRAL_NORM "100.000000"

I could not find any documentation on SPECTRAL_NORM on argyllcms.com,
but the source code file xspect.h has this comment:
double norm; /* Normalising scale value, ie. 1, 100 etc. */

The ISO 28178:2009 standard does not mention SPECTRAL_NORM, but does have these 2 lines:
SPECTRAL_PCT - Reflectance/transmittance percentage
SPECTRAL_DEC - Reflectance/transmittance

Argyll CMS does not use these; what about i1Profiler ?

Hope this helps,
Glenn

[KelSolaar]

Hi @diuming and @glenndavis52,

I have quickly checked the standard and the keyword does not exist unfortunately, nor there is any reference to a normalisation specification.

Cheers,

Thomas