Graeme, 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, compute XYZ and graph the resulted "instrument locus" over the Standard Observer spectrum locus on a chromaticity diagram? Roger -----Original Message----- From: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx] On Behalf Of Graeme Gill Sent: September-02-11 9:17 AM To: argyllcms@xxxxxxxxxxxxx Subject: [argyllcms] Re: Argyll V1.3.4 released To get some idea about how close the filters are to the standard observer, I did the following: For a set of display sample XYZ values of the primaries + white, for each pair of calibration matrices for the different display types, I computed the CIEDE2000 between the values predicted by the two matrices. Over the 147 combinations, there was an average error of 0.798 DE, and a maximum of 4.72. I think this hints that the instruments will perform very well across different types of displays. Graeme Gill.