  In this work, we propose proLab: a new colour coordinate system derived as a
3D projective transformation of CIE XYZ. We show that proLab is far ahead of
the widely used CIELAB coordinate system (though inferior to the modern
CAM16-UCS) according to perceptual uniformity evaluated by the STRESS metric in
reference to the CIEDE2000 colour difference formula. At the same time, angular
errors of chromaticity estimation that are standard for linear colour spaces
can also be used in proLab since projective transformations preserve the
linearity of manifolds. Unlike in linear spaces, angular errors for different
hues are normalized according to human colour discrimination thresholds within
proLab. We also demonstrate that shot noise in proLab is more homoscedastic
than in CAM16-UCS or other standard colour spaces. This makes proLab a
convenient coordinate system in which to perform linear colour analysis.
