Setting a property of a control in another project to a resource of the local project

[Hamish]

I hope this is easier to explain than it is to describe, but I doubt it.
I'm still working on the Canvas version of the PictureBox_ColorMap.
Here's the code for my class:

Imports System.Windows.Controls
Imports System.Windows.Media.Imaging
Imports System.Drawing
Imports System.Windows.Input

Public Class ColorMapCanvas
	Inherits Canvas

	Private _ColorMap As Bitmap
	Private _RaiseEventOnMouseMove As Boolean = True
	Private _RaiseEventOnMouseLeftButtonDown As Boolean = True

	Public Event ColorMapMouseLeftButtonDown(ByVal sender As Object, ByVal ReturnedColor As Color)
	Public Event ColorMapMouseMove(ByVal sender As Object, ByVal ReturnedColor As Color)

	Public Property ColorMap() As Bitmap
		Get
			Return _ColorMap
		End Get
		Set(ByVal value As Bitmap)
			_ColorMap = value
		End Set
	End Property

	Public Property RaiseEventOnMouseMove() As Boolean
		Get
			Return _RaiseEventOnMouseMove
		End Get
		Set(ByVal value As Boolean)
			_RaiseEventOnMouseMove = value
		End Set
	End Property

	Public Property RaiseEventOnMouseLeftButtonDown() As Boolean
		Get
			Return _RaiseEventOnMouseLeftButtonDown
		End Get
		Set(ByVal value As Boolean)
			_RaiseEventOnMouseLeftButtonDown = value
		End Set
	End Property

	Protected Overrides Sub OnMouseLeftButtonDown(ByVal e As MouseButtonEventArgs)
		Dim p As System.Windows.Point = e.GetPosition(Me)
		MyBase.OnMouseLeftButtonDown(e)
		If _RaiseEventOnMouseLeftButtonDown Then
			If Not _ColorMap Is Nothing AndAlso p.X <= _ColorMap.Width AndAlso p.Y <= _ColorMap.Height Then
				RaiseEvent ColorMapMouseLeftButtonDown(Me, _ColorMap.GetPixel(CInt(p.X), CInt(p.Y)))
			Else
				RaiseEvent ColorMapMouseLeftButtonDown(Me, Nothing)
			End If
		End If
	End Sub

	Protected Overrides Sub OnMouseMove(ByVal e As MouseEventArgs)
		Dim p As System.Windows.Point = e.GetPosition(Me)
		MyBase.OnMouseMove(e)
		If _RaiseEventOnMouseMove Then
			If Not _ColorMap Is Nothing AndAlso p.X <= _ColorMap.Width AndAlso p.Y <= _ColorMap.Height Then
				RaiseEvent ColorMapMouseMove(Me, _ColorMap.GetPixel(CInt(p.X), CInt(p.Y)))
			Else
				RaiseEvent ColorMapMouseMove(Me, Nothing)
			End If
		End If
	End Sub

End Class

Now in my XAML (in another project, I keep my custom controls together in a seperate project) I have this:

<Controls:ColorMapCanvas x:Name="MapCanvas" Width="8980" Height="5160">
	<Canvas.Background>
		<ImageBrush x:Name="CanvasBrush" ImageSource="/Resources/TempMainMap.png" ScrollViewer.CanContentScroll="True"/>
	</Canvas.Background>
</Controls:ColorMapCanvas>

I want to add setting the ColorMap property of my ColorMapCanvas control to use another resource in the same project as the XAML. I tried using:

<Controls:ColorMapCanvas x:Name="MapCanvas" ColorMap="/Resources/TempColorMap.png" Width="8980" Height="5160">

But that gives me an error "Parameter is not valid." on the ColorMap property.
I can think of 2 reasons this may happen, but can't think of a solution for either.

1. The "/Resources/TempColorMap.png" isn't a Bitmap, but a BitmapSource.
2. The ColorMapCanvas control can't access the image to be used because it's in another project.

So, can anyone tell me which of these (or something I haven't thought of) it is, and what to do about it?