Contex XD2490 Service Manual page 46

Appendix - C --- Scanner Terms
brightness (luminance) component Y (as described above), and
two additional components X and Z. The spectral weighting
curves of X and Z have been standardized by the CIE, based
on statistics from experiments involving human observers.
XYZ tri-stimulus values can describe any color.
Zoom
The ability to enlarge or shrink the view of the picture in a
window. Zoom does not alter the size of the final scanned pic-
ture; it only provides a better view while creating a selection
border on the screen.
C-8