Added Luminance meter

com.unity.render-pipelines.high-definition/HDRP/Debug/DebugColorPicker.shader

                 //Decompress value if luxMeter is active
                 if (_DebugLightingMode == DEBUGLIGHTINGMODE_LUX_METER && _ColorPickerMode != COLORPICKERDEBUGMODE_NONE)
                     result.rgb = result.rgb * LUXMETER_COMPRESSION_RATIO;
+                    
+                if (_DebugLightingMode == DEBUGLIGHTINGMODE_LUMINANCE_METER)
+                {
+                    result = Luminance(result.rgb);
+                }
 
                 if (_FalseColor)
                     result.rgb = FasleColorRemap(Luminance(result.rgb), _FalseColorThresholds);

com.unity.render-pipelines.high-definition/HDRP/Debug/LightingDebug.cs

         DiffuseLighting,
         SpecularLighting,
         LuxMeter,
+        LuminanceMeter,
         VisualizeCascade,
         VisualizeShadowMasks,
         IndirectDiffuseOcclusion,

com.unity.render-pipelines.high-definition/HDRP/Debug/LightingDebug.cs.hlsl

 #define DEBUGLIGHTINGMODE_DIFFUSE_LIGHTING (1)
 #define DEBUGLIGHTINGMODE_SPECULAR_LIGHTING (2)
 #define DEBUGLIGHTINGMODE_LUX_METER (3)
-#define DEBUGLIGHTINGMODE_VISUALIZE_CASCADE (4)
-#define DEBUGLIGHTINGMODE_VISUALIZE_SHADOW_MASKS (5)
-#define DEBUGLIGHTINGMODE_INDIRECT_DIFFUSE_OCCLUSION (6)
-#define DEBUGLIGHTINGMODE_INDIRECT_SPECULAR_OCCLUSION (7)
-#define DEBUGLIGHTINGMODE_SCREEN_SPACE_TRACING_REFRACTION (8)
-#define DEBUGLIGHTINGMODE_SCREEN_SPACE_TRACING_REFLECTION (9)
+#define DEBUGLIGHTINGMODE_LUMINANCE_METER (4)
+#define DEBUGLIGHTINGMODE_VISUALIZE_CASCADE (5)
+#define DEBUGLIGHTINGMODE_VISUALIZE_SHADOW_MASKS (6)
+#define DEBUGLIGHTINGMODE_INDIRECT_DIFFUSE_OCCLUSION (7)
+#define DEBUGLIGHTINGMODE_INDIRECT_SPECULAR_OCCLUSION (8)
+#define DEBUGLIGHTINGMODE_SCREEN_SPACE_TRACING_REFRACTION (9)
+#define DEBUGLIGHTINGMODE_SCREEN_SPACE_TRACING_REFLECTION (10)
 
 //
 // UnityEngine.Experimental.Rendering.HDPipeline.DebugScreenSpaceTracing:  static fields

com.unity.render-pipelines.high-definition/HDRP/RenderPipeline/HDRenderPipeline.cs

 
         public void PushColorPickerDebugTexture(CommandBuffer cmd, RTHandleSystem.RTHandle textureID, HDCamera hdCamera)
         {
-            if (m_CurrentDebugDisplaySettings.colorPickerDebugSettings.colorPickerMode != ColorPickerDebugMode.None || m_DebugDisplaySettings.falseColorDebugSettings.falseColor)
+            if (m_CurrentDebugDisplaySettings.colorPickerDebugSettings.colorPickerMode != ColorPickerDebugMode.None || m_DebugDisplaySettings.falseColorDebugSettings.falseColor || m_DebugDisplaySettings.lightingDebugSettings.debugLightingMode == DebugLightingMode.LuminanceMeter)
             {
                 using (new ProfilingSample(cmd, "Push To Color Picker"))
                 {
         // TODO TEMP: Not sure I want to keep this special case. Gotta see how to get rid of it (not sure it will work correctly for non-full viewports.
         public void PushColorPickerDebugTexture(HDCamera hdCamera, CommandBuffer cmd, RenderTargetIdentifier textureID)
         {
-            if (m_CurrentDebugDisplaySettings.colorPickerDebugSettings.colorPickerMode != ColorPickerDebugMode.None || m_DebugDisplaySettings.falseColorDebugSettings.falseColor)
+            if (m_CurrentDebugDisplaySettings.colorPickerDebugSettings.colorPickerMode != ColorPickerDebugMode.None || m_DebugDisplaySettings.falseColorDebugSettings.falseColor || m_DebugDisplaySettings.lightingDebugSettings.debugLightingMode == DebugLightingMode.LuminanceMeter)
             {
                 using (new ProfilingSample(cmd, "Push To Color Picker"))
                 {
 
                 DecalSystem.instance.RenderDebugOverlay(hdCamera, cmd, m_CurrentDebugDisplaySettings, ref x, ref y, overlaySize, hdCamera.actualWidth);
 
-                if (m_CurrentDebugDisplaySettings.colorPickerDebugSettings.colorPickerMode != ColorPickerDebugMode.None || m_CurrentDebugDisplaySettings.falseColorDebugSettings.falseColor)
+                if (m_CurrentDebugDisplaySettings.colorPickerDebugSettings.colorPickerMode != ColorPickerDebugMode.None || m_CurrentDebugDisplaySettings.falseColorDebugSettings.falseColor || m_CurrentDebugDisplaySettings.lightingDebugSettings.debugLightingMode == DebugLightingMode.LuminanceMeter)
                 {
                     ColorPickerDebugSettings colorPickerDebugSettings = m_CurrentDebugDisplaySettings.colorPickerDebugSettings;
                     FalseColorDebugSettings falseColorDebugSettings = m_CurrentDebugDisplaySettings.falseColorDebugSettings;