# colour.ATD95_Specification¶

class colour.ATD95_Specification[source]

Defines the ATD (1995) colour vision model specification.

This specification has field names consistent with the remaining colour appearance models in colour.appearance but diverge from Fairchild (2013) reference.

Parameters
• h (numeric or array_like) – Hue angle $$H$$ in degrees.

• C (numeric or array_like) – Correlate of saturation $$C$$. Guth (1995) incorrectly uses the terms saturation and chroma interchangeably. However, $$C$$ is here a measure of saturation rather than chroma since it is measured relative to the achromatic response for the stimulus rather than that of a similarly illuminated white.

• Q (numeric or array_like) – Correlate of brightness $$Br$$.

• A_1 (numeric or array_like) – First stage $$A_1$$ response.

• T_1 (numeric or array_like) – First stage $$T_1$$ response.

• D_1 (numeric or array_like) – First stage $$D_1$$ response.

• A_2 (numeric or array_like) – Second stage $$A_2$$ response.

• T_2 (numeric or array_like) – Second stage $$A_2$$ response.

• D_2 (numeric or array_like) – Second stage $$D_2$$ response.

Notes

• This specification is the one used in the current model implementation.

References

Create new instance of ATD95_Specification(h, C, Q, A_1, T_1, D_1, A_2, T_2, D_2)

__init__()

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

Methods

 __init__ Initialize self. count(value) index(value, [start, [stop]]) Raises ValueError if the value is not present.

Attributes

 A_1 Alias for field number 3 A_2 Alias for field number 6 C Alias for field number 1 D_1 Alias for field number 5 D_2 Alias for field number 8 Q Alias for field number 2 T_1 Alias for field number 4 T_2 Alias for field number 7 h Alias for field number 0