colour_hdri.generation Package

Sub-Modules

• colour_hdri.generation.radiance Module
  • HDRI / Radiance Image Generation
• colour_hdri.generation.weighting_functions Module
  • Weighting Functions

Module Contents

colour_hdri.generation.normal_distribution_function(a, mu=0.5, sigma=0.15)

Returns given array weighted by a normal distribution function.

Parameters:

• a (array_like) – Array to apply the weighting function onto.
• mu (numeric, optional) – Mean or expectation.
• sigma (numeric, optional) – Standard deviation.

Returns:

Weighted array.

Return type:

ndarray

Examples

>>> normal_distribution_function(np.linspace(0, 1, 10))
array([ 0.00386592,  0.03470859,  0.18002174,  0.53940751,  0.93371212,
        0.93371212,  0.53940751,  0.18002174,  0.03470859,  0.00386592])

colour_hdri.generation.hat_function(a)

Returns given array weighted by a hat function.

Parameters:a (array_like) – Array to apply the weighting function onto. Returns:Weighted array. Return type:ndarray

Examples

>>> hat_function(np.linspace(0, 1, 10))
array([ 0.        ,  0.95099207,  0.99913557,  0.99999812,  1.        ,
        1.        ,  0.99999812,  0.99913557,  0.95099207,  0.        ])

colour_hdri.generation.weighting_function_Debevec1997(a, domain_l=0.01, domain_h=0.99)

Returns given array weighted by Debevec (1997) function.

Parameters:

• a (array_like) – Array to apply the weighting function onto.
• domain_l (numeric, optional) – Domain lowest possible value, values less than domain_l will be set to zero.
• domain_h (numeric, optional) – Domain highest possible value, values greater than domain_h will be set to zero.

Returns:

Weighted array.

Return type:

ndarray

References

[1]	Debevec, P., & Malik, J. (1997). Recovering High Dynamic Range Radiance Maps from Photographs, (August), 1–10. doi:10.1145/258734.258884

Examples

>>> weighting_function_Debevec1997(np.linspace(0, 1, 10))
array([ 0.        ,  0.23273657,  0.48849105,  0.74424552,  1.        ,
        1.        ,  0.74424552,  0.48849105,  0.23273657,  0.        ])

colour_hdri.generation.image_stack_to_radiance_image(image_stack, weighting_function=<function weighting_function_Debevec1997>, weighting_average=False, camera_response_functions=None)

Generates a HDRI / radiance image from given image stack.

Parameters:

• image_stack (ImageStack) – Stack of single channel or multi-channel floating point images. The stack is assumed to be representing linear values except if camera_response_functions argument is provided.
• weighting_function (callable, optional) – Weighting function \(w\).
• weighting_average (bool, optional) – Enables weighting function \(w\) computation on channels average instead of on a per channel basis.
• camera_response_functions (array_like, optional) – Camera response functions \(g(z)\) of the imaging system / camera if the stack is representing non linear values.

Returns:

Radiance image.

Return type:

ndarray