# colour.constants.cie Module¶

## CIE Constants¶

Defines CIE constants.

colour.constants.cie.CIE_E = 0.008856451679035631

CIE $$\epsilon$$ constant.

CIE_E : numeric

Notes

• The original CIE value for $$\epsilon$$ is $$\epsilon=0.008856$$, Bruce Lindbloom has shown that this value is causing a discontinuity a the junction point of the two functions grafted together to create the Lightness $$L^*$$ function.

That discontinuity can be avoided by using the rational representation as follows: $$\epsilon=216/24389$$.

References

 [1] http://brucelindbloom.com/index.html?LContinuity.html (Last accessed 24 February 2014)
colour.constants.cie.CIE_K = 903.2962962962963

CIE $$k$$ constant.

CIE_K : numeric

Notes

• The original CIE value for $$k$$ is $$k=903.3$$, Bruce Lindbloom has shown that this value is causing a discontinuity a the junction point of the two functions grafted together to create the Lightness $$L^*$$ function.

That discontinuity can be avoided by using the rational representation as follows: $$k=24389/27$$.

References

 [2] http://brucelindbloom.com/index.html?LContinuity.html (Last accessed 24 February 2014)