Re Re: mgfilt, degree Kelvin into spectral data

Hi Christian,

The two spectra do not have to be normalized to the same value. In fact, you can multiply the cspec output by mgfilt by the lumens of your light source and the transmission of your filter (between 0 and 1 at each wavelength) and get something related to the lumen output over the spectrum.

Man pages for MGF can be found on the website -- I assumed you had this:



From: Christian Fusenig <[email protected]>
Date: April 6, 2006 2:39:33 AM PDT

Thanks for your answer Greg,
The normalization of the spectral power distribution is unimportant, but I believe mgfilt outputs something that sums to 1.0 when integrated with the photopic curve. Whatever it comes out to, the actual value is normalized by the reflectance or emission it's applied to. Since you aren't applying it to anything, it doesn't matter.
The problem is, i am applying the spectrum of this lamp to a color filter spectrum.
The spectral data of this filter is normalized to 1 or 100%. There are values from 0,0000 up to 1.
If i multiply these two spectra as shown in "Rendering with Radiance" p.435, i think the data should be normalized
to the same standard, or am i wrong?
My output is a combined spectrum and then i convert it back to CIExy values, then with to RGB.
Thats why i want to know how mgfilt works and what it is capable of. Is there any man page?