I can't figure how to animate the material of a UI Image

I’m working with an artist on a UI based game and he wants to have a smooth “blend to white” effect on an image. The game is in black and white.

I wrote a very simple shader that clamps the minimum value of rgb to a float value between 0 and 1.
I made a material out of it and made a testing script that would change this material.

We want to achieve this effect !
Alt text)

At first I thought it did not work because of the UI Image not being instantiated like meshes material, so I sort of instantiated my material to reassign it at runtime (I’m not sure it would actually change anything I’m just poking in the dark here)

Here’s my code anyway :

 private Image myImage;

    public Material instanceOfMat;
    public Shader shader;
    public Color blendColor;
    public float blendStrengh;

    // Use this for initialization
    void Awake () {
        myImage = GetComponent<Image>();
        instanceOfMat = new Material(shader);
        instanceOfMat.SetColor("Blend Color", blendColor);
        instanceOfMat.SetFloat("Flashing White", blendStrengh);
    }
	
	// Update is called once per frame
	void Update () {
        instanceOfMat.SetColor("Blend Color", blendColor);
        instanceOfMat.SetFloat("Flashing White", blendStrengh);
        myImage.material = instanceOfMat;
    }

But it does not work at all and I’m out of solutions, maybe I’m not considering the problem the right way !
Thank you very much !

Also here’s my Fragment shader

 fixed4 frag(v2f i) : SV_Target
    			{
    				fixed4 blendStr = _BlendStrengh;
    				// Sample the texture and blend with color
    				fixed4 col = tex2D(_MainTex, i.uv) * _BlendColor;
    				//Adjust how intense is the white flash
    				col.r = clamp(col.r, blendStr, 1);
    				col.g = clamp(col.g, blendStr, 1);
    				col.b = clamp(col.b, blendStr, 1);
    
    				return col;
    			}

Nevermind ! I was giving the property editor’s name (blendColor) and not the shader name (_BlendColor)