 rgb2hex = () ->
     [r,g,b] = unpack arguments
     u = r << 16 | g << 8 | b
-    str = "000000" + u.toString(16).toUpperCase()
+    str = "000000" + u.toString(16) #.toUpperCase()
     "#" + str.substr(str.length - 6)
 
 


    hsi: ->
        rgb2hsi @_rgb

    interpolate: (f, col, m) ->
        ###

        if chroma.colors? and chroma.colors[hex]
            hex = chroma.colors[hex]
        else
            throw "unknown color: "+hex
    if hex.length == 4 or hex.length == 7
        hex = hex.substr(1)
    if hex.length == 3
