Passing parameters to fullscreen shader (noob question)

Im trying to make a full screen colorcorrection shader (camera shader).
For that i want to be able to adjust parameters directly on my camera, and then pass them onto the shader when needed.

I have made a little test. I have added a parameter called "Gamma" that i want to move from the C# code onto the shader. However im not sure how i can do it.

So in my C# file that i attach to the camera i add:

Code (CSharp):

1. using System;
2. using UnityEngine;
3.  
4. namespace UnityStandardAssets.ImageEffects
5. {
6.     [ExecuteInEditMode]
7.     [AddComponentMenu("MyShaders/CustomColor")]
8.     public class CustomColor : ImageEffectBase
9.     {
10.         public Color gamma = Color.white; // This is the value i want to pass
11.         void OnRenderImage (RenderTexture source, RenderTexture destination)
12.         {
13.             Graphics.Blit (source, destination, material);
14.         }
15.     }
16. }

And then i have the shader:

Code (CSharp):

1. Shader "Hidden/CustomColor" {
2. Properties {
3.     _MainTex ("Base (RGB)", 2D) = "white" {}
4.     _Gamma ("Gamma", Color) = (1.0,1.0,1.0,1.0)
5. }
6.  
7. SubShader {
8.     Pass {
9.         ZTest Always Cull Off ZWrite Off
10.              
11. CGPROGRAM
12. #pragma vertex vert_img
13. #pragma fragment frag
14. #include "UnityCG.cginc"
15.  
16. uniform sampler2D _MainTex;
17. uniform float _Gamma; //The color i want to get!
18.  
19. fixed3 frag (v2f_img i) : SV_Target
20. {  
21.     fixed3 original = tex2D(_MainTex, i.uv);
22.     float lift = 0.0;
23.     //float gamma = 0.5;
24.     float gain = 1.0;
25.  
26.     //LiftGammaGain
27.     fixed3 LGG = pow( gain*(original.rgb + lift*(1-original.rgb)) ,(1/_Gamma)); //sudo code, won't work yet
28.     output = LGG;
29.     return output;
30. }
31. ENDCG
32.  
33.     }
34. }
35.  
36. Fallback off
37.  
38. }
39.  

 

To answer my own question:

material.SetColor("_Gamma",gamma);