Fix bug in homography detection
Explicitly cast image shape to integer value
Add some more comments
Re-enable clipping which was accidentally removed
Do not derive piecewise affine from projective transform
Luv colorspace conversions

Adding XYZ <--> Luv, RGB <-->
Adding test functions to mirror Lab tests
Adding references regarding Lab and Luv spaces to docstring
Removing unneeded division checking code
renaming machineEps to eps to match convention
flake8-compliant formatting
Cleaning up docstrings
docstring changes to correctly format input/output, clarifying XYZ and reference white
Adding note for Luv colorspace to top docstring
Merge pull request #796 from ahojnnes/warp-fix

Fix bug in homography detection
Make six an external dependency.
Add python-six as Travis dependency.
Install six from PyPi.  Travis version is too old.
Format color conversion docstrings.
Merge pull request #1 from stefanv/luv-colorspace

Format color conversion docstrings.
Modify mpl_image_to_rgba to allow RGB input image

mpl_image_to_rgba produces a image of shape (M, N, 3, 4) when the input
image is already RGB. This is understandably confusing for downstream
processes, and this commit fixes it.