Comments by Mike-MadBadger (Top 15 by date)

Let's see if I've understood:
The classes, as conceived, don't think at all about actual drawing, they are just objects to manage colors, either color models or color spaces plus the conversions and the transitions between spaces and models (which is often confused). A color space being the manner in which a model becomes something real rather than abstract.

However, I think you are suggesting this:
A class called Color which contains as a member an interface, let's call it IColorModel.
The classes that manage the color models must implement IColorModel, RGB, CMYK etc.
The Color class should have a second member called IColorSpace which allows the model to be interpreted in such a way that it can be rendered correctly.
Color model conversions, e.g. RGB to CMYK, simply change the IColorModel member.
Color space changes, e.g. CIE 1931 XYZ to Adobe RGB change the IColorSpace member and have consequent changes on the IColorModel member, either a complete change or a change in the detail: CIELAB to sRGB would change both, Adobe RGB to sRGB would change the space and the detail of the model.
The ToGray methods, as an example, would call the relavant method of the IColor member which would probably also implement the IColorToGrey interface, both interface members pointing at the same actual object.

Have I understood anything?

aCMYK newColor = new aCMYK();
newColor.ToGrey(GreyScaleMethod.RedChannel)

Public Interface IToGrey
Sub ToGrey(ByRef color As IColorModelConvertible)
End Interface

Public Interface IColorModelConvertible
Function ToARGB(Optional ByVal alpha As Integer = 255) As aRGB
Function ToColor(Optional ByVal alpha As Integer = 255) As Color
Function ToAHSB() As aHSB
Function ToAHSL() As aHSL
Function ToACMYK() As aCMYK
Function ToHex(Optional ByVal alpha As Integer = 255) As String
End Interface

Public Class RGBAverage
Implements IToGrey
Public Sub ToGrey(ByRef color As IColorModelConvertible) Implements IToGrey.ToGrey
Dim newARGB As aRGB = color.ToARGB()
newRGB.Green = newRGB.Red()
newRGB.Blue = newRGB.Red()
color = newRGB.To [Help: Don't know original class type!)
End Sub

Out of interest (sorry for the delay) why custom rather than InvalidEnumArgumentException or ArgumentOutOfRangeException?
I get the idea / benefit of writing your own exceptions, however those two seem pretty well aligned with the problem at hand?

Struggled a bit to understand your articles, they are, at least as yet, a bit ahead of me - hopefully I'll get there sooner or later.
I did however find this: http://blogs.microsoft.co.il/blogs/gilf/archive/2009/11/22/applying-strategy-pattern-instead-of-using-switch-statements.aspx
I found it be a usefully simpler explanation for my level.