unity 改变图片亮度，饱和度，对比度

shader

cg 复制代码

Shader "Custom/Brightness_Saturation_And_Contrast"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
        _Brightness ("Brightess", Float) = 1.0
        _Saturation ("Saturation", Float) = 1.0
        _Contrast ("Contrast", Float) = 1.0
    }
    SubShader
    {
        Cull Off ZWrite Off ZTest Always

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            
            #include "UnityCG.cginc"

            struct a2f
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

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

            sampler2D _MainTex;
            half _Brightness;
            half _Saturation;
            half _Contrast;

            v2f vert (a2f v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
                //采样
                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;  //计算该像素的亮度值
                fixed3 luminanceColor = fixed3(luminance, luminance, luminance);  //创建饱和度为0的颜色
                finalColor = lerp(luminanceColor, finalColor, _Saturation);
               
                //对比度
                fixed3 avgColor = fixed3(0.5, 0.5, 0.5);
                finalColor = lerp(avgColor, finalColor, _Contrast);

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

通过组件进行调用

csharp 复制代码

public class ColorAdjust : MonoBehaviour
{
    private static readonly int Brightess = Shader.PropertyToID("_Brightess");
    private static readonly int Saturation = Shader.PropertyToID("_Saturation");
    private static readonly int Contrast = Shader.PropertyToID("_Contrast");
    
    /// <summary>
    /// 颜色材质
    /// </summary>
    public Material colorMaterial;
    
    public void Render(RenderTexture src, RenderTexture dest, float brightess, float saturation, float contrast) 
    {
        if (colorMaterial == null) {
            Debug.LogError("材质球为空");
            return;
        }
        
        colorMaterial.SetFloat(Brightess, brightess);
        colorMaterial.SetFloat(Saturation, saturation);
        colorMaterial.SetFloat(Contrast, contrast);
        
        Graphics.Blit(src, dest, colorMaterial);
    }
}

调用

csharp 复制代码

ColorAdjust colorAdjust = self.RawImage.GetComponent<ColorAdjust>();
RenderTexture initRt = RenderTexture.GetTemporary(initTx.width, initTx.height, 0);
RenderTexture destRt = RenderTexture.GetTemporary(initTx.width, initTx.height, 0);
//亮度
colorAdjust.Render(initRt, destRt, value, 1, 1);
//饱和度
colorAdjust.Render(initRt, destRt, 1, value, 1);
//对比度
colorAdjust.Render(initRt, destRt, 1, 1, value);