colour_hdri.calibration.absolute_luminance Module¶

Absolute Luminance Calibration - Lagarde (2016)¶

Defines Lagarde (2016) panoramic images absolute Luminance calibration objects:

absolute_luminance_calibration_Lagarde2016()
upper_hemisphere_illuminance_Lagarde2016()
upper_hemisphere_illuminance_weights_Lagarde2016()

References

[1]	Lagarde, S., Lachambre, S., & Jover, C. (2016). An Artist-Friendly Workflow for Panoramic HDRI. Retrieved from http://blog.selfshadow.com/publications/s2016-shading-course/unity/s2016_pbs_unity_hdri_notes.pdf

colour_hdri.calibration.absolute_luminance.upper_hemisphere_illuminance_Lagarde2016(RGB, colourspace=None)[source]¶

Computes upper hemisphere illuminance \(E_v\) of given RGB panoramic image.

Parameters:	RGB (array_like) – RGB panoramic image array. colourspace (colour.RGB_Colourspace, optional) – RGB colourspace used for internal Luminance computation.
Returns:	Upper hemisphere illuminance \(E_v\).
Return type:	numeric

Examples

>>> RGB = np.ones((16, 32, 3))
>>> upper_hemisphere_illuminance_Lagarde2016(RGB)  # doctest: +ELLIPSIS
2.9344691...

colour_hdri.calibration.absolute_luminance.upper_hemisphere_illuminance_weights_Lagarde2016(height, width)[source]¶

Computes upper hemisphere illuminance weights for use with applications unable to perform the computation directly, i.e. Adobe Photoshop.

Parameters:	height (int) – Output array height. width (int) – Output array width.
Returns:	Upper hemisphere illuminance weights.
Return type:	ndarray

Examples

>>> upper_hemisphere_illuminance_weights_Lagarde2016(  # doctest: +ELLIPSIS
...    16, 1)
array([[ 0...        ],
       [ 4.0143297...],
       [ 7.3345454...],
       [ 9.3865515...],
       [ 9.8155376...],
       [ 8.5473281...],
       [ 5.8012079...],
       [ 2.0520061...],
       [ 0...        ],
       [ 0...        ],
       [ 0...        ],
       [ 0...        ],
       [ 0...        ],
       [ 0...        ],
       [ 0...        ],
       [ 0...        ]])

colour_hdri.calibration.absolute_luminance.absolute_luminance_calibration_Lagarde2016(RGB, measured_illuminance, colourspace=None)[source]¶

Performs absolute Luminance calibration of given RGB panoramic image using Lagarde (2016) method.

Parameters:	RGB (array_like) – RGB panoramic image to calibrate. measured_illuminance (numeric) – Measured illuminance \(E_v\). colourspace (colour.RGB_Colourspace, optional) – RGB colourspace used for internal Luminance computation.
Returns:	Absolute Luminance calibrated RGB panoramic image.
Return type:	ndarray

Examples

>>> RGB = np.ones((4, 8, 3))
>>> absolute_luminance_calibration_Lagarde2016(  # doctest: +ELLIPSIS
...     RGB, 500)
array([[[ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...]],
<BLANKLINE>
       [[ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...]],
<BLANKLINE>
       [[ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...]],
<BLANKLINE>
       [[ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...],
        [ 233.9912506...,  233.9912506...,  233.9912506...]]])