后处理 - 亮度，饱和度，对比度

效果

c#代码

using UnityEngine;

public class MyBrightnessSaturationAndContrast : MonoBehaviour
{

    public Shader m_Shader;
    public Material m_Material;

    [Range(0.0f, 3.0f)]
    public float m_brightness = 1.0f;

    [Range(0.0f, 3.0f)]
    public float m_saturation = 1.0f;

    [Range(0.0f, 3.0f)]
    public float m_contrast = 1.0f;

    void Start()
    {
        if (false == SystemInfo.supportsImageEffects)
        {
            Debug.LogWarning("This platform does not support image effects or render textures.");
            this.enabled = false;
            return;
        }

        if (null == m_Material)
        {
            if (null != m_Shader && m_Shader.isSupported)
            {
                m_Material = new Material(m_Shader);
                m_Material.hideFlags = HideFlags.DontSave;
            }
        }
        else if (m_Material.shader != m_Shader)
        {
            if (m_Shader.isSupported) //优先shader
            {
                m_Material = new Material(m_Shader);
                m_Material.hideFlags = HideFlags.DontSave;
            }
        }
    }

    void OnRenderImage(RenderTexture src, RenderTexture dest)
    {
        if (null != m_Material)
        {
            m_Material.SetFloat("_Brightness", m_brightness);
            m_Material.SetFloat("_Saturation", m_saturation);
            m_Material.SetFloat("_Contrast", m_contrast);

            Graphics.Blit(src, dest, m_Material);
        }
        else
        {
            Graphics.Blit(src, dest);
        }
    }

}

shader

Shader "My/PostEff/BrightnessSaturationAndContrast"
{
	Properties
	{
		_MainTex("Base (RGB)", 2D) = "white" {}
		_Brightness("Brightness", Float) = 1
		_Saturation("Saturation", Float) = 1
		_Contrast("Contrast", Float) = 1
	}

	SubShader
	{
		Tags { "RenderType" = "Opaque" }
		LOD 100

		Pass
		{
			ZTest Always
			Cull Off
			ZWrite Off

			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag

			#include "UnityCG.cginc"

			sampler2D _MainTex;
			float4 _MainTex_ST;

			half _Brightness;
			half _Saturation;
			half _Contrast;

			struct appdata
			{
				float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
			};

			struct v2f
			{
				float2 uv : TEXCOORD0;
				float4 vertex : SV_POSITION;
			};

			v2f vert(appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.uv = TRANSFORM_TEX(v.uv, _MainTex);
				return o;
			}

			fixed4 frag(v2f i) : SV_Target
			{
				fixed4 renderTex = tex2D(_MainTex, i.uv);

				//亮度
				fixed3 finalColor = renderTex.rgb * _Brightness;

				//饱和度
				fixed luminance = 0.2125 * renderTex.r + 0.7154 * renderTex.g + 0.0721 * renderTex.b;
				fixed3 luminanceColor = fixed3(luminance, luminance, luminance); //饱和度为0的颜色值
				finalColor = lerp(luminanceColor, finalColor, _Saturation); //饱和度为0~某个饱和度

				//对比度
				fixed3 avgColor = fixed3(0.5, 0.5, 0.5); //对比度为0的颜色值
				finalColor = lerp(avgColor, finalColor, _Contrast);

				return fixed4(finalColor, renderTex.a);
			}
			ENDCG
		}
	}

	Fallback Off
}