マテリアル-PPMでLUT

UE4：ver.4.19.0

まだデフォルトのLUTでもON/OFFで若干色味が変わってしまってるっぽい？

テストしたマテリアル手順

1. LUTテクスチャの設定を下記に
   1. Filterを “Tri-linear” に
   2. Texture Groupを “ColorLookupTable” に
2. Mateiralの設定を下記に
   1. Mateiral Domainを “Post Process” に
   2. Blendable Locatinを “Before Tonemapping” に
3. ノードを下記に
   
4. Customノードはこんな感じ

   static const float LUTSize = 16;
   
   #if POST_PROCESS_MATERIAL
   
   // ColorLookupTable
   {
   
   
   	// sRGBToLinear
   	{
   		LinearColor = max(6.10352e-5, LinearColor); // minimum positive non-denormal (fixes black problem on DX11 AMD and NV)
   		LinearColor = LinearColor > 0.04045 ? pow( LinearColor * (1.0 / 1.055) + 0.0521327, 2.4 ) : LinearColor * (1.0 / 12.92);
   	}
   	
   	float3 LUTEncodedColor;
   #if 0 // if( r.HDR.Display.OutputDevice >= 3 )
   	
   	// LinearToST2084
   	{
   		const float m1 = 0.1593017578125; // = 2610. / 4096. * .25;
   		const float m2 = 78.84375; // = 2523. / 4096. *  128;
   		const float c1 = 0.8359375; // = 2392. / 4096. * 32 - 2413./4096.*32 + 1;
   		const float c2 = 18.8515625; // = 2413. / 4096. * 32;
   		const float c3 = 18.6875; // = 2392. / 4096. * 32;
   		const float C = 10000.;
   
   		float3 L = LinearColor/C;
   		float3 Lm = pow(L, m1);
   		float3 N1 = ( c1 + c2 * Lm );
   		float3 N2 = ( 1.0 + c3 * Lm );
   		float3 N = N1 * rcp(N2);
   		float3 P = pow( N, m2 );
   		
   		LUTEncodedColor = P;
   	}
   #else
   	 float LinearRange = 14;
   	 float LinearGrey = 0.18;
   	 float ExposureGrey = 444;
   	 float3 Lin;
   	 // LogToLin(0)
   	 {
   		Lin = exp2( ( float3(0,0,0) - ExposureGrey / 1023.0 ) * LinearRange ) * LinearGrey;
   	 }
   
   	// LinToLog
   	{
   		
   		// Using stripped down, 'pure log', formula. Parameterized by grey points and dynamic range covered.
   		float3 LogColor = log2(LinearColor + Lin) / LinearRange - log2(LinearGrey) / LinearRange + ExposureGrey / 1023.0;	// scalar: 3log2 3mad
   		//float3 LogColor = (log2(LinearColor) - log2(LinearGrey)) / LinearRange + ExposureGrey / 1023.0;
   		//float3 LogColor = log2( LinearColor / LinearGrey ) / LinearRange + ExposureGrey / 1023.0;
   		//float3 LogColor = (0.432699 * log10(0.5 * LinearColor + 0.037584) + 0.616596) + 0.03;	// SLog
   		//float3 LogColor = ( 300 * log10( LinearColor * (1 - .0108) + .0108 ) + 685 ) / 1023;	// Cineon
   		LogColor = saturate( LogColor );
   		
   		LUTEncodedColor = LogColor;
   	}
   #endif
   	
   	
   	float3 UVW = LUTEncodedColor * ((LUTSize - 1) / LUTSize) + (0.5f / LUTSize);
   	
   	float3 OutputColor = UnwrappedTexture3DSample( TextureLUT, TextureLUTSampler, UVW, LUTSize ).rgb;
   	OutputColor = OutputColor * 1.05;
   	
   	
   	// sRGBToLinear
   	{
   		// OutputColor = max(6.10352e-5, OutputColor); // minimum positive non-denormal (fixes black problem on DX11 AMD and NV)
   		// OutputColor = OutputColor > 0.04045 ? pow( OutputColor * (1.0 / 1.055) + 0.0521327, 2.4 ) : OutputColor * (1.0 / 12.92);
   	}
   
   
   	return OutputColor;
   }
   #else
   return float3(0,0,0);
   #endif