Roger Breton wrote: > To get some idea about how close the filters are to the standard observer, I > thought one had to measure the whole 380 to 730 spectrum, using a 1nm (or > not too larger) spectrograph, to break the spectrum into "lines", so that > one can get the response of the colorimeter at that particular wavelength, This information is stored in the instrument. > compute XYZ and graph the resulted "instrument locus" over the Standard > Observer spectrum locus on a chromaticity diagram? Hmm. I haven't done this, but apart from an interesting visual comparison, it wouldn't give a quantifiable measurement. I've certainly overlaid the instrument curves and standard observer curves (although each instrument is slightly different). Graeme Gill.