class colour.quality.CQS_Specification[source]

Defines the Colour Quality Scale (CQS) colour quality specification.

  • name (unicode) – Name of the test spectral distribution.
  • Q_a (numeric) – Colour quality scale \(Q_a\).
  • Q_f (numeric) – Colour fidelity scale \(Q_f\) intended to evaluate the fidelity of object colour appearances (compared to the reference illuminant of the same correlated colour temperature and illuminance).
  • Q_p (numeric) – Colour preference scale \(Q_p\) similar to colour quality scale \(Q_a\) but placing additional weight on preference of object colour appearance. This metric is based on the notion that increases in chroma are generally preferred and should be rewarded.
  • Q_g (numeric) – Gamut area scale \(Q_g\) representing the relative gamut formed by the (\(a^*\), \(b^*\)) coordinates of the 15 samples illuminated by the test light source in the CIE L*a*b* object colourspace.
  • Q_d (numeric) – Relative gamut area scale \(Q_d\).
  • Q_as (dict) – Individual Colour Quality Scale (CQS) data for each sample.
  • colorimetry_data (tuple) – Colorimetry data for the test and reference computations.


[DO10], [OD08]

Create new instance of CQS_Specification(name, Q_a, Q_f, Q_p, Q_g, Q_d, Q_as, colorimetry_data)


Initialize self. See help(type(self)) for accurate signature.


count Return number of occurrences of value.
index Return first index of value.


Q_a Alias for field number 1
Q_as Alias for field number 6
Q_d Alias for field number 5
Q_f Alias for field number 2
Q_g Alias for field number 4
Q_p Alias for field number 3
colorimetry_data Alias for field number 7
name Alias for field number 0