Vipscol_Ch2ab

void
vips_col_Ch2ab (
  float C,
  float h,
  float* a,
  float* b
)

Calculate ab from Ch, h in degrees.

`C`	`float`
	Chroma.
`h`	`float`
	Hue angle (degrees)
`a`	`float*`
	Return CIE a* value.
	The data is owned by the caller of the function.
`b`	`float*`
	Return CIE b* value.
	The data is owned by the caller of the function.