UnityShader 亮度、饱和度、对比度的实现

fixed4 col = tex2D(_MainTex, i.uv);

亮度 _Brightness

//亮度直接叠加
fixed3 color = col.rgb*_Brightness;

饱和度 _Saturation

//饱和度=最低灰度颜色与原图的差值
fixed3 gray = fixed3(0.2125, 0.7154, 0.0721);
fixed minGray = dot(gray, col.rgb);
fixed3 grayColor = fixed3(minGray, minGray, minGray);
color = lerp(grayColor, color, _Saturation);

对比度 _Contrast

//对比度=最低对比度图像(0.5,0.5,0.5)与原图的差值
fixed3 minContrast = fixed3(0.5, 0.5, 0.5);
color = lerp(minContrast, color, _Contrast);