toPolar {spacesXYZ}

Convert CIE Lab and Luv to Polar Form

Description

Convert the Rectangular Form of CIE Lab and Luv to Polar Form

Usage

LCHabfromLab( Lab ) 
LCHuvfromLuv( Luv ) 

Arguments

Lab

a numeric Nx3 matrix with CIE Lab coordinates in the rows, or a vector that can be converted to such a matrix, by row.

Luv

a numeric Nx3 matrix with CIE Luv coordinates in the rows, or a vector that can be converted to such a matrix, by row.

Value

a numeric Nx3 matrix with LCH coordinates in the rows. The lightness L is simply copied from input to output. The chroma C corresponds to radius in polar coordinates, and the hue H corresponds to theta. H is in degrees, not radians. The rownames are copied from input to output.

References

Wikipedia. CIE 1931 color space. https://en.wikipedia.org/wiki/CIE_1931_color_space

See Also

LabfromLCHab(), LuvfromLCHuv()

Examples

LCHabfromLab( c(50,0,0) )   #  a neutral gray
##        L Cab Hab
##  [1,] 50   0   0         # Hue is undefined, but set to 0

LCHabfromLab( c(50,0,20) ) 
##        L Cab Hab
##  [1,] 50  20  90         # 90 degrees, on yellow axis


LCHabfromLab( c(50,0,-20) ) 
##        L Cab Hab
##  [1,] 50  20 270         # 270 degrees, on blue axis