Remove reference to Bento hookfile.
Modified 'denoise_bilateral':\n1) check that image max value is not zero to avoid segmentation fault.\n2) initialize color_lut after sigma_range has been checked.
Deported variable initialization after the cdef block to allow verifications.
Moved image conversion after the verification of the max_value
Merge pull request #576 from alexis-mignon/master

Bugs in filter.denoise_biltateral.
Added a function for Gamma Correction
Prevented info loss, implemented Log and Sigmoid Correction
Separating the functions
Separating correction methods into different functions
Correcting code quality issues
Added better tests and removed weak ones
Added stronger tests
Corrections and Improvements
Minor improvements in docs, tests
Error handling for images with negative values in Image Correction methods
Adding a utility function to test non-negativity of an image
Renaming rescale_intensity_* as adjust_*
Replacing every occurence of substract* with subtract*
Merge pull request #581 from ankit-maverick/subtract

STY: Replacing every occurence of ``substract*`` with ``subtract*``.
Final stylistic changes in exposure.py