Inverse model computation:

1. Compute achromatic white point of the target device using equations 4.82 and 4.83.

2. Compute brightness Q from lightness J:

(4.94)

3. Compute achromatic signal A from lightness J

(4.95)

(4.96)

4. Compute chroma C from colorfulness M

(4.97)

5. Compute color opponents a & b from chroma C and hue h

(4.98)

6. Compute cone signals LMS from the achromatic signal A and opponents a & b

(4.99)

7. Compute cone signals LMS from nonlinear cone signals

(4.100)

8. Compute tristimulus from cone signals LMS using the HPE transform.

Apply inverse CIECAT02 transform (using target white).

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