error plot for lab color coordinates

This function can be used to illustrate error values related to datapoints of CIE-L*a*b* color coordinates. A larger error is plotted by a larger marker, or in quiver plots by longer vectors.
This is useful to illustrate for instance color differences of reconstructed color coordinates or reconstructed spectral reflectance data. Also other errors realted to the data can be illustrated, eg. RMSE (the errors have to be normalized to a maximum value of 1).

Illustrating errors in Lab plots allows to identify dependencies of the error with color. The quiver plots allow to identify global or local trends of the errors.

-> Run 'plot_Lab_error(0,0,0,0,0)' for a demo of all plot types!!

-> Note: depending on the error value range used, 'vec_scale' and 'err_scale' (line 47 and 49) might require to be adjusted to the data.

-> if you are looking only for a way to illustrate Lab color coordinates, check 'plot_Lab.m' in Matlab File Exchange (http://www.mathworks.com/matlabcentral/fileexchange/44965).

-> the figures can be exported to scalable vector graphics (svg) usoing 'plot2svg.m' by Juerg Schwizer (http://www.mathworks.es/matlabcentral/fileexchange/7401-scalable-vector-graphics-svg-export-of-figures)