Pixelation Filter

////////////////////////////////////////////////
////////////////////CPU SIDE////////////////////
////////////////////////////////////////////////
using UnityEngine;
using System.Collections;

[ExecuteInEditMode]
public class Pixelation : MonoBehaviour
{
    public float pixelX, pixelY;
    private Material material;

    void Awake()
    {
        material = new Material(Shader.Find("My Shaders/Pixelation")); //Use the shader.
    }

    void OnRenderImage(RenderTexture source, RenderTexture destination) //Before the buffer is sent to the camera, modify it with above shader.
    {
        material.SetFloat("_PixelCountX", pixelX); //Uniform the value to the shader.
        material.SetFloat("_PixelCountY", pixelY); //Uniform the value to the shader.
        Graphics.Blit(source, destination, material); //Blit the modified image to the screen.
    }
}

////////////////////////////////////////////////
////////////////////GPU SIDE////////////////////
////////////////////////////////////////////////
Shader "My Shaders/Pixelation"
{
    Properties
    {
        _MainTex ("Buffer", 2D) = "white" {}
        _PixelCountX ("Number of X", float) = 128 //Xres default value.
        _PixelCountY ("Number of Y", float) = 72 //Yres default value.
    }
    SubShader
    {
        Pass
        {
            CGPROGRAM

            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

            sampler2D _MainTex;
            float _PixelCountX;
            float _PixelCountY;

            struct vertexOutput
            {
                float4 position : SV_POSITION;
                float2 texCoord : TEXCOORD0;
            };

            vertexOutput vert(appdata_base vIn) //Passthrough
            {
                vertexOutput output;
                output.texCoord = vIn.texcoord.xy;
                output.position = mul(UNITY_MATRIX_MVP, vIn.vertex);

                return output;
            }

            float4 frag(vertexOutput input) : COLOR
            {
                //Get the percentages of the screen per pixel.
                float pixelWidth = 1.0f / _PixelCountX;
                float pixelHeight = 1.0f / _PixelCountY;


                float2 texCoord = float2((int)(input.texCoord.x / pixelWidth) * pixelWidth, (int)(input.texCoord.y / pixelHeight) * pixelHeight);
                float4 colour = tex2D(_MainTex, texCoord); //Redraw the buffer using our new, low resolution texture coordinates.

                return colour;
            }
            ENDCG
        }
    }
}