[R] grDevices::convertColor XYZ space is it really xyY?

2013-06-12 Thread Bryan Hanson
grDevices::convertColor has arguments 'from' and 'to' which can take on value 'XYZ'. Can someone confirm that 'XYZ' is the same as the CIE chromaticity coordinates that are also sometimes refered to as 'xyY' in the literature? Or are these the CIE tristimulus values? It looks to me like the

Re: [R] grDevices::convertColor XYZ space is it really xyY?

2013-06-12 Thread Duncan Murdoch
On 12/06/2013 2:45 PM, Bryan Hanson wrote: grDevices::convertColor has arguments 'from' and 'to' which can take on value 'XYZ'. Can someone confirm that 'XYZ' is the same as the CIE chromaticity coordinates that are also sometimes refered to as 'xyY' in the literature? Or are these the CIE

Re: [R] grDevices::convertColor XYZ space is it really xyY?

2013-06-12 Thread Ken Knonlauch
Bryan Hanson hanson at depauw.edu writes: grDevices::convertColor has arguments 'from' and 'to' which can take on value 'XYZ'. Can someone confirm that 'XYZ' is the same as the CIE chromaticity coordinates are also sometimes refered to as 'xyY' in the literature? Or are these the CIE

Re: [R] grDevices::convertColor XYZ space is it really xyY?

2013-06-12 Thread Bryan Hanson
Ken, I followed your suggestion and perhaps I don't understand what to expect from convertColor or maybe I'm not using it correctly. Consider the following tests: D65 - c(0.3127, 0.329, 0.3583) # D65 chromaticity coordinates X - D65[1]*D65[3]/D65[2] # conversion per brucelindbloom.com Y -

Re: [R] grDevices::convertColor XYZ space is it really xyY?

2013-06-12 Thread Ken Knoblauch
You seem to treating the input values as xyY when they should be XYZ (case matters). So, I would do something like this D65 - c(0.3127, 0.329, 0.3583) X - 100 * D65[1] Y - 100 * D65[2] Z - 100 * D65[3] XYZ - data.frame(X = X, Y = Y, Z = Z) convertColor(XYZ, from = XYZ, to = sRGB) [,1]

Re: [R] grDevices::convertColor XYZ space is it really xyY?

2013-06-12 Thread Bryan Hanson
Thank you Ken. 90% of my problem was missing the factor of 100. I was just inputing xyY as a test, I wasn't sure whether the docs were being clear about nomenclature. Speaking thereof, the D65 values used in the example: I thought they were chromaticity coordinates, but apparently they are

Re: [R] grDevices::convertColor XYZ space is it really xyY?

2013-06-12 Thread Ken Knoblauch
If they sum to 1 then they are one and the same. Look at how chromaticity coordinates are defined in terms of the tristimulus values. Quoting Bryan Hanson han...@depauw.edu: Thank you Ken. 90% of my problem was missing the factor of 100. I was just inputing xyY as a test, I wasn't sure