Table 65 – Entries in a Lab Colour Space Dictionary

Key

Type

Value

WhitePoint

array

(Required) An array of three numbers [ X W Y W Z W ] that shall specify the tristimulus value, in the CIE 1931 XYZ space, of the diffuse white point; see 8.6.5.3, "CalRGB Colour Spaces" for further discussion. The numbers X W and Z W shall be positive, and Y W shall be 1.0.

BlackPoint

array

(Optional) An array of three numbers [ X B Y B Z B ] that shall specify the tristimulus value, in the CIE 1931 XYZ space, of the diffuse black point; see 8.6.5.3, "CalRGB Colour Spaces" for further discussion. All three of these numbers shall be non-negative. Default value: [ 0.0 0.0 0.0 ].

Range

array

(Optional) An array of four numbers [ a min a max b min b max ] that shall specify the range of valid values for the a* and b* (B and C) components of the colour space—that is,

amina* amax≤≤

and

bminb* bmax≤≤

Component values falling outside the specified range shall be adjusted to the nearest valid value without error indication.

Default value: [−100 100 −100 100 ].