hsv2rgb rgb2hsv conversion (the hue value may have a different scale)

hsv2rgb.coffee

hsv2rgb = ([h,s,v])->
  return [v,v,v] if s is 0
  h  = if h >= 1 then h - 1 else h
  hh = h * 6
  hhh = Math.floor hh
  f = hh - hhh
  a = v * (1.0 - s)
  b = v * (1.0 - s * f)
  c = v * (1.0 - s * (1 - f))
  return switch hhh
    when 0 then [ Math.round(v * 255), Math.round(c * 255), Math.round(a * 255) ]
    when 1 then [ Math.round(b * 255), Math.round(v * 255), Math.round(a * 255) ]
    when 2 then [ Math.round(a * 255), Math.round(v * 255), Math.round(c * 255) ]
    when 3 then [ Math.round(a * 255), Math.round(b * 255), Math.round(v * 255) ]
    when 4 then [ Math.round(c * 255), Math.round(a * 255), Math.round(v * 255) ]
    when 5 then [ Math.round(v * 255), Math.round(a * 255), Math.round(b * 255) ]

rgb2hsv.coffee

rgb2hsv = ([r,g,b])->
 r=r/255
 g=g/255
 b=b/255;
 v = Math.max(r, Math.max(g,b));
 min = Math.min(r, Math.min(g,b));
 return [0,0,0] if v is 0
 d = v - min
 s = d / v
 if r is v
	 h = (g - b) / d
 else if g is v
   h = ((b - r) / d) + 2
 else
	 h = ((r - g) / d) + 4
 h /= 6
 h += 1 if h < 0
 [h,s,v]