Phlips Hue - RGB Color Feedback - Zigbee

[admin]

Use this conversion function:

Code:

function xytorgb(x, y, level)
  local function revgamma(v)
    if v <= 0.0031308 then
      return v * 12.92
    else
      return (1 + 0.055) * math.pow(v, (1 / 2.4)) - 0.055
    end
  end

  local function clampconvert(v, max)
    v = math.max(0, v * 255 / max)
    v = math.min(255, v)
    return math.round(v)
  end

  local x = x / 0xFFFE
  local y = y / 0xFFFE
  local z = 1 - x - y

  local Y = math.min(254, level) / 254
  local X = (Y / y) * x
  local Z = (Y / y) * z

  local r = revgamma(3.2404542 * X - 1.5371385 * Y - 0.4985314 * Z)
  local g = revgamma(-0.9692660 * X + 1.8760108 * Y + 0.0415560 * Z)
  local b = revgamma(0.0556434 * X - 0.2040259 * Y + 1.0572252 * Z)

  local max = math.max(r, g, b)

  r = clampconvert(r, max)
  g = clampconvert(g, max)
  b = clampconvert(b, max)

  return r * 0x10000 + g * 0x100 + b
end

x = 45913
y = 19614
level = 254

rgb = xytorgb(x, y, level)
log(rgb)

You also need to pass the light level (0..254) for the conversion to work.