[idd/client] correct HDR luminance when PQ conversion is in use

`linear` is a HLSL keyword

client/displayservers/Wayland/CMakeLists.txt

@@ -13,6 +13,7 @@ find_program(WAYLAND_SCANNER_EXECUTABLE NAMES wayland-scanner)
 add_library(displayserver_Wayland STATIC
   activation.c
   clipboard.c
+  colormgmt.c
   cursor.c
   gl.c
   idle.c

client/displayservers/Wayland/colormgmt.c

@@ -0,0 +1,110 @@
+/**
+ * Looking Glass
+ * Copyright (C) 2017-2026 The Looking Glass Authors
+ * https://looking-glass.io
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc., 59
+ * Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include "wayland.h"
+
+#include <stdbool.h>
+
+#include <wayland-client.h>
+
+#include "common/debug.h"
+
+static void cmIntent(void * data, struct wp_color_manager_v1 * cm, uint32_t intent)
+{
+  if (intent == WP_COLOR_MANAGER_V1_RENDER_INTENT_PERCEPTUAL)
+    wlWm.cmHasPerceptualIntent = true;
+}
+
+static void cmFeature(void * data, struct wp_color_manager_v1 * cm, uint32_t feature)
+{
+  switch (feature)
+  {
+    case WP_COLOR_MANAGER_V1_FEATURE_PARAMETRIC:
+      wlWm.cmHasParametric = true;
+      break;
+    case WP_COLOR_MANAGER_V1_FEATURE_SET_LUMINANCES:
+      wlWm.cmHasLuminances = true;
+      break;
+    case WP_COLOR_MANAGER_V1_FEATURE_SET_MASTERING_DISPLAY_PRIMARIES:
+      wlWm.cmHasMasteringPrimaries = true;
+      break;
+    default:
+      break;
+  }
+}
+
+static void cmTFNamed(void * data, struct wp_color_manager_v1 * cm, uint32_t tf)
+{
+  if (tf == WP_COLOR_MANAGER_V1_TRANSFER_FUNCTION_ST2084_PQ)
+    wlWm.cmHasTFSt2084PQ = true;
+  else if (tf == WP_COLOR_MANAGER_V1_TRANSFER_FUNCTION_EXT_LINEAR)
+    wlWm.cmHasTFExtLinear = true;
+}
+
+static void cmPrimariesNamed(void * data, struct wp_color_manager_v1 * cm,
+    uint32_t primaries)
+{
+  if (primaries == WP_COLOR_MANAGER_V1_PRIMARIES_BT2020)
+    wlWm.cmHasPrimariesBT2020 = true;
+  else if (primaries == WP_COLOR_MANAGER_V1_PRIMARIES_SRGB)
+    wlWm.cmHasPrimariesSRGB = true;
+}
+
+static void cmDone(void * data, struct wp_color_manager_v1 * cm)
+{
+  wlWm.cmFeaturesDone = true;
+  wlWm.cmCanDoHDR = wlWm.cmHasParametric &&
+    ((wlWm.cmHasTFSt2084PQ && wlWm.cmHasPrimariesBT2020) ||
+     (wlWm.cmHasTFExtLinear && wlWm.cmHasPrimariesSRGB));
+  DEBUG_INFO("Color management features: parametric:%d luminances:%d "
+      "mastering_primaries:%d st2084_pq:%d ext_linear:%d bt2020:%d srgb:%d "
+      "can_do_hdr:%d",
+      wlWm.cmHasParametric, wlWm.cmHasLuminances,
+      wlWm.cmHasMasteringPrimaries,
+      wlWm.cmHasTFSt2084PQ, wlWm.cmHasTFExtLinear,
+      wlWm.cmHasPrimariesBT2020, wlWm.cmHasPrimariesSRGB,
+      wlWm.cmCanDoHDR);
+}
+
+static const struct wp_color_manager_v1_listener cmListener = {
+  .supported_intent          = cmIntent,
+  .supported_feature         = cmFeature,
+  .supported_tf_named        = cmTFNamed,
+  .supported_primaries_named = cmPrimariesNamed,
+  .done                      = cmDone,
+};
+
+bool waylandColorMgmtInit(void)
+{
+  if (!wlWm.colorManager)
+    return true;
+
+  wp_color_manager_v1_add_listener(wlWm.colorManager, &cmListener, NULL);
+  return true;
+}
+
+void waylandColorMgmtFree(void)
+{
+  if (!wlWm.colorManager)
+    return;
+
+  wp_color_manager_v1_destroy(wlWm.colorManager);
+  wlWm.colorManager = NULL;
+}

client/displayservers/Wayland/gl.c

@@ -70,6 +70,52 @@ EGLDisplay waylandGetEGLDisplay(void)
   return eglGetDisplay(native);
 }
 
+static void applyHDRPending(void)
+{
+  if (wlWm.pendingHDRApply)
+  {
+    wlWm.pendingHDRApply = false;
+    atomic_thread_fence(memory_order_acquire);
+    waylandSetHDRImageDescription(
+        wlWm.pendingHDRDisplayPrimary, wlWm.pendingHDRWhitePoint,
+        wlWm.pendingHDRMaxDisplayLuminance,
+        wlWm.pendingHDRMinDisplayLuminance,
+        wlWm.pendingHDRMaxCLL,
+        wlWm.pendingHDRMaxFALL,
+        wlWm.pendingHDRPQ);
+  }
+  else if (wlWm.pendingHDRClear)
+  {
+    wlWm.pendingHDRClear = false;
+    waylandClearHDRImageDescription();
+  }
+}
+
+void waylandClearHDRImageDescription(void)
+{
+  if (!wlWm.hdrActive)
+    return;
+
+  if (wlWm.hdrImageCreator)
+  {
+    wp_image_description_creator_params_v1_destroy(wlWm.hdrImageCreator);
+    wlWm.hdrImageCreator = NULL;
+  }
+  if (wlWm.hdrImageDesc)
+  {
+    wp_image_description_v1_destroy(wlWm.hdrImageDesc);
+    wlWm.hdrImageDesc = NULL;
+  }
+  if (wlWm.colorSurface)
+  {
+    wp_color_management_surface_v1_destroy(wlWm.colorSurface);
+    wlWm.colorSurface = NULL;
+  }
+
+  wlWm.hdrActive = false;
+  DEBUG_INFO("HDR image description cleared");
+}
+
 void waylandEGLSwapBuffers(EGLDisplay display, EGLSurface surface, const struct Rect * damage, int count)
 {
   if (!wlWm.swapWithDamage.init)
@@ -84,6 +130,7 @@ void waylandEGLSwapBuffers(EGLDisplay display, EGLSurface surface, const struct
   }
 
   waylandPresentationFrame();
+  applyHDRPending();
   swapWithDamage(&wlWm.swapWithDamage, display, surface, damage, count);
 
   if (wlWm.needsResize)
@@ -149,23 +196,239 @@ EGLNativeWindowType waylandGetEGLNativeWindow(void)
 }
 #endif
 
+// HDR color management support
+void waylandSetHDRImageDescription(const uint16_t displayPrimary[3][2],
+    const uint16_t whitePoint[2], uint32_t maxDisplayLuminance,
+    uint32_t minDisplayLuminance, uint32_t maxCLL, uint32_t maxFALL,
+    bool hdrPQ)
+{
+  if (!wlWm.colorManager)
+    return;
+
+  if (!wlWm.cmFeaturesDone)
+  {
+    DEBUG_WARN("Color management features not yet advertised, deferring HDR");
+    return;
+  }
+
+  if (!wlWm.cmHasParametric)
+  {
+    DEBUG_WARN("Compositor does not support parametric image descriptions");
+    return;
+  }
+
+  // Verify the compositor supports the transfer function we need
+  if (hdrPQ && !wlWm.cmHasTFSt2084PQ)
+  {
+    DEBUG_WARN("Compositor does not support ST2084_PQ transfer function");
+    return;
+  }
+  if (!hdrPQ && !wlWm.cmHasTFExtLinear)
+  {
+    DEBUG_WARN("Compositor does not support EXT_LINEAR transfer function");
+    return;
+  }
+
+  // Verify primaries support for the target color space
+  if (hdrPQ && !wlWm.cmHasPrimariesBT2020)
+  {
+    DEBUG_WARN("Compositor does not support BT.2020 primaries");
+    return;
+  }
+  if (!hdrPQ && !wlWm.cmHasPrimariesSRGB)
+  {
+    DEBUG_WARN("Compositor does not support sRGB primaries");
+    return;
+  }
+
+  // Clean up any previous description (allows re-application with updated metadata)
+  if (wlWm.hdrImageCreator)
+  {
+    wp_image_description_creator_params_v1_destroy(wlWm.hdrImageCreator);
+    wlWm.hdrImageCreator = NULL;
+  }
+  if (wlWm.hdrImageDesc)
+  {
+    wp_image_description_v1_destroy(wlWm.hdrImageDesc);
+    wlWm.hdrImageDesc = NULL;
+  }
+  if (wlWm.colorSurface)
+  {
+    wp_color_management_surface_v1_destroy(wlWm.colorSurface);
+    wlWm.colorSurface = NULL;
+  }
+
+  wlWm.hdrActive = false;
+
+  wlWm.hdrImageCreator =
+    wp_color_manager_v1_create_parametric_creator(wlWm.colorManager);
+  if (!wlWm.hdrImageCreator)
+  {
+    DEBUG_WARN("Failed to create parametric image description creator");
+    return;
+  }
+
+  // Set primaries: BT.2020 for PQ HDR10, sRGB for scRGB/FP16
+  wp_image_description_creator_params_v1_set_primaries_named(
+      wlWm.hdrImageCreator,
+      hdrPQ ? WP_COLOR_MANAGER_V1_PRIMARIES_BT2020
+            : WP_COLOR_MANAGER_V1_PRIMARIES_SRGB);
+
+  // Select transfer function: PQ for PQ-encoded content, linear for scRGB/FP16
+  wp_image_description_creator_params_v1_set_tf_named(
+      wlWm.hdrImageCreator,
+      hdrPQ ? WP_COLOR_MANAGER_V1_TRANSFER_FUNCTION_ST2084_PQ
+            : WP_COLOR_MANAGER_V1_TRANSFER_FUNCTION_EXT_LINEAR);
+
+  // Set luminance range from metadata.
+  // min_lum is in 0.0001 cd/m² units (multiplied by 10000 as per protocol).
+  // max_lum and reference_lum are in unscaled cd/m² units.
+  if (wlWm.cmHasLuminances)
+    wp_image_description_creator_params_v1_set_luminances(
+        wlWm.hdrImageCreator,
+        minDisplayLuminance > 0 ? minDisplayLuminance : 50,
+        maxDisplayLuminance > 0 ? maxDisplayLuminance / 10000 : 1000,
+        hdrPQ                   ? 203                         : 80);
+
+  // Set mastering display primaries from frame HDR metadata.
+  // Always set when the compositor supports it, falling back to the
+  // primaries from the metadata (even if zero, in which case the
+  // compositor uses its own defaults).
+  if (wlWm.cmHasMasteringPrimaries)
+  {
+    wp_image_description_creator_params_v1_set_mastering_display_primaries(
+        wlWm.hdrImageCreator,
+        displayPrimary[0][0], displayPrimary[0][1],
+        displayPrimary[1][0], displayPrimary[1][1],
+        displayPrimary[2][0], displayPrimary[2][1],
+        whitePoint[0], whitePoint[1]);
+
+    // Set mastering luminance range so the compositor knows the target
+    // color volume for tone mapping.  min_lum is in ×10000 units (0.0001 cd/m²),
+    // max_lum is in unscaled cd/m².
+    wp_image_description_creator_params_v1_set_mastering_luminance(
+        wlWm.hdrImageCreator,
+        minDisplayLuminance > 0 ? minDisplayLuminance : 50,
+        maxDisplayLuminance > 0 ? maxDisplayLuminance / 10000 : 1000);
+  }
+
+  if (maxCLL > 0)
+    wp_image_description_creator_params_v1_set_max_cll(wlWm.hdrImageCreator, maxCLL);
+  if (maxFALL > 0)
+    wp_image_description_creator_params_v1_set_max_fall(wlWm.hdrImageCreator, maxFALL);
+
+  wlWm.hdrImageDesc =
+    wp_image_description_creator_params_v1_create(wlWm.hdrImageCreator);
+  wlWm.hdrImageCreator = NULL; // consumed by create
+
+  if (!wlWm.hdrImageDesc)
+  {
+    DEBUG_WARN("Failed to create HDR image description");
+    return;
+  }
+
+  wlWm.colorSurface =
+    wp_color_manager_v1_get_surface(wlWm.colorManager, wlWm.surface);
+  if (!wlWm.colorSurface)
+  {
+    DEBUG_WARN("Failed to get color management surface");
+    wp_image_description_v1_destroy(wlWm.hdrImageDesc);
+    wlWm.hdrImageDesc = NULL;
+    return;
+  }
+
+  wp_color_management_surface_v1_set_image_description(
+      wlWm.colorSurface, wlWm.hdrImageDesc,
+      WP_COLOR_MANAGER_V1_RENDER_INTENT_PERCEPTUAL);
+
+  wlWm.hdrActive = true;
+  DEBUG_INFO("HDR image description set on surface (%s, %s, %u nits)",
+      hdrPQ ? "PQ" : "scRGB", hdrPQ ? "BT.2020" : "sRGB", maxDisplayLuminance);
+}
+
+bool waylandRequestHDR(const uint16_t displayPrimary[3][2],
+    const uint16_t whitePoint[2], uint32_t maxDisplayLuminance,
+    uint32_t minDisplayLuminance, uint32_t maxCLL, uint32_t maxFALL,
+    bool hdrPQ)
+{
+  if (!wlWm.cmFeaturesDone || !wlWm.cmHasParametric)
+    return false;
+  if (hdrPQ && !wlWm.cmHasTFSt2084PQ)
+    return false;
+  if (!hdrPQ && !wlWm.cmHasTFExtLinear)
+    return false;
+  if (hdrPQ && !wlWm.cmHasPrimariesBT2020)
+    return false;
+  if (!hdrPQ && !wlWm.cmHasPrimariesSRGB)
+    return false;
+
+  wlWm.pendingHDRPQ = hdrPQ;
+
+  // Write all metadata before setting the apply flag to ensure the
+  // render thread sees the complete HDR metadata when it observes
+  // pendingHDRApply == true.
+  memcpy(wlWm.pendingHDRDisplayPrimary, displayPrimary,
+      sizeof(wlWm.pendingHDRDisplayPrimary));
+  memcpy(wlWm.pendingHDRWhitePoint, whitePoint,
+      sizeof(wlWm.pendingHDRWhitePoint));
+  wlWm.pendingHDRMaxDisplayLuminance = maxDisplayLuminance;
+  wlWm.pendingHDRMinDisplayLuminance = minDisplayLuminance;
+  wlWm.pendingHDRMaxCLL              = maxCLL;
+  wlWm.pendingHDRMaxFALL             = maxFALL;
+
+  wlWm.pendingHDRClear = false;
+  atomic_thread_fence(memory_order_release);
+  wlWm.pendingHDRApply = true;
+  return true;
+}
+
+void waylandRequestClearHDR(void)
+{
+  wlWm.pendingHDRClear = true;
+  wlWm.pendingHDRApply = false;
+}
+
 #ifdef ENABLE_OPENGL
+
+static const EGLint eglBaseAttrs[] =
+{
+  EGL_CONFORMANT       , EGL_OPENGL_BIT,
+  EGL_RENDERABLE_TYPE  , EGL_OPENGL_BIT,
+  EGL_COLOR_BUFFER_TYPE, EGL_RGB_BUFFER,
+  EGL_SAMPLE_BUFFERS   , 0,
+  EGL_SAMPLES          , 0,
+  EGL_NONE
+};
+
+static bool eglChooseConfigWithDepth(EGLDisplay display, EGLint red,
+    EGLint green, EGLint blue, EGLint alpha, EGLint depth,
+    EGLConfig * config, const char ** desc)
+{
+  // Build attr array with the base attrs plus color depth
+  EGLint attr[32];
+  int   ai = 0;
+  attr[ai++] = EGL_RED_SIZE  ; attr[ai++] = red;
+  attr[ai++] = EGL_GREEN_SIZE; attr[ai++] = green;
+  attr[ai++] = EGL_BLUE_SIZE ; attr[ai++] = blue;
+  attr[ai++] = EGL_ALPHA_SIZE; attr[ai++] = alpha;
+  attr[ai++] = EGL_BUFFER_SIZE; attr[ai++] = depth;
+  for (int i = 0; eglBaseAttrs[i] != EGL_NONE; ++i)
+    attr[ai++] = eglBaseAttrs[i];
+  attr[ai] = EGL_NONE;
+
+  EGLint num_config;
+  if (eglChooseConfig(display, attr, config, 1, &num_config) && num_config > 0)
+  {
+    if (desc)
+      *desc = red >= 16 ? "FP16 (RGBA16F)" :
+              red >= 10 ? "10-bit (RGBA10)" : "8-bit (RGBA8)";
+    return true;
+  }
+  return false;
+}
+
 bool waylandOpenGLInit(void)
 {
-  EGLint attr[] =
-  {
-    EGL_BUFFER_SIZE      , 24,
-    EGL_CONFORMANT       , EGL_OPENGL_BIT,
-    EGL_RENDERABLE_TYPE  , EGL_OPENGL_BIT,
-    EGL_COLOR_BUFFER_TYPE, EGL_RGB_BUFFER,
-    EGL_RED_SIZE         , 8,
-    EGL_GREEN_SIZE       , 8,
-    EGL_BLUE_SIZE        , 8,
-    EGL_SAMPLE_BUFFERS   , 0,
-    EGL_SAMPLES          , 0,
-    EGL_NONE
-  };
-
   wlWm.glDisplay = waylandGetEGLDisplay();
 
   int maj, min;
@@ -181,13 +444,31 @@ bool waylandOpenGLInit(void)
     return false;
   }
 
-  EGLint num_config;
-  if (!eglChooseConfig(wlWm.glDisplay, attr, &wlWm.glConfig, 1, &num_config))
+  EGLConfig config;
+  const char * configDesc = NULL;
+
+  // Probe for best available color depth: FP16 → 10-bit → 8-bit
+  if (!eglChooseConfigWithDepth(wlWm.glDisplay,
+        16, 16, 16, 0, 48, &config, &configDesc) &&
+      !eglChooseConfigWithDepth(wlWm.glDisplay,
+        10, 10, 10, 2, 32, &config, &configDesc) &&
+      !eglChooseConfigWithDepth(wlWm.glDisplay,
+        8, 8, 8, 0, 24, &config, &configDesc))
   {
-    DEBUG_ERROR("Failed to choose config (eglError: 0x%x)", eglGetError());
+    DEBUG_ERROR("Failed to choose any EGL config");
     return false;
   }
 
+  wlWm.glConfig = config;
+  DEBUG_INFO("EGL config: %s", configDesc);
+
+  // Also store the 8-bit fallback for SDR contexts
+  if (configDesc && strcmp(configDesc, "8-bit (RGBA8)") != 0)
+    eglChooseConfigWithDepth(wlWm.glDisplay,
+        8, 8, 8, 0, 24, &wlWm.glConfigSDR, NULL);
+  else
+    wlWm.glConfigSDR = wlWm.glConfig;
+
   wlWm.glSurface = eglCreateWindowSurface(wlWm.glDisplay, wlWm.glConfig, wlWm.eglWindow, NULL);
   if (wlWm.glSurface == EGL_NO_SURFACE)
   {

client/displayservers/Wayland/protocol/CMakeLists.txt

@@ -66,6 +66,9 @@ wayland_generate(
 wayland_generate(
   "${WAYLAND_PROTOCOLS_BASE}/staging/content-type/content-type-v1.xml"
   "${CMAKE_BINARY_DIR}/wayland/wayland-content-type-v1-client-protocol")
+wayland_generate(
+  "${WAYLAND_PROTOCOLS_BASE}/staging/color-management/color-management-v1.xml"
+  "${CMAKE_BINARY_DIR}/wayland/wayland-color-management-v1-client-protocol")
 
 target_link_libraries(wayland_protocol
   PkgConfig::WAYLAND

client/displayservers/Wayland/registry.c

@@ -74,6 +74,9 @@ static void registryGlobalHandler(void * data, struct wl_registry * registry,
   else if (!strcmp(interface, wp_content_type_manager_v1_interface.name))
     wlWm.contentTypeManager = wl_registry_bind(wlWm.registry, name,
         &wp_content_type_manager_v1_interface, 1);
+  else if (!strcmp(interface, wp_color_manager_v1_interface.name))
+    wlWm.colorManager = wl_registry_bind(wlWm.registry, name,
+        &wp_color_manager_v1_interface, 1);
   else if (wlWm.desktop->registryGlobalHandler(
         data, registry, name, interface, version))
     return;

client/displayservers/Wayland/wayland.c

@@ -28,6 +28,7 @@
 
 #include "common/debug.h"
 #include "common/option.h"
+#include "interface/renderer.h"
 
 #include "dynamic/wayland_desktops.h"
 
@@ -143,6 +144,9 @@ static bool waylandInit(const LG_DSInitParams params)
   if (!waylandRegistryInit())
     return false;
 
+  if (!waylandColorMgmtInit())
+    return false;
+
   if (!waylandActivationInit())
     return false;
 
@@ -189,6 +193,7 @@ static void waylandFree(void)
   waylandPresentationFree();
   waylandInputFree();
   waylandOutputFree();
+  waylandColorMgmtFree();
   waylandRegistryFree();
   waylandCursorFree();
   wl_display_disconnect(wlWm.display);
@@ -202,6 +207,12 @@ static bool waylandGetProp(LG_DSProperty prop, void * ret)
     return true;
   }
 
+  if (prop == LG_DS_NATIVE_HDR)
+  {
+    *(bool *)ret = wlWm.cmCanDoHDR;
+    return true;
+  }
+
   return false;
 }
 
@@ -227,6 +238,22 @@ static void waylandMinimize(void)
   wlWm.desktop->minimize();
 }
 
+static bool waylandHDRCallback(const void * rendererFormat)
+{
+  if (!wlWm.colorManager)
+    return false;
+
+  const LG_RendererFormat * format = (const LG_RendererFormat *)rendererFormat;
+  if (format->hdr)
+    return waylandRequestHDR(format->hdrDisplayPrimary, format->hdrWhitePoint,
+        format->hdrMaxDisplayLuminance, format->hdrMinDisplayLuminance,
+        format->hdrMaxContentLightLevel, format->hdrMaxFrameAverageLightLevel,
+        format->hdrPQ);
+  else
+    waylandRequestClearHDR();
+  return true;
+}
+
 struct LG_DisplayServerOps LGDS_Wayland =
 {
   .name                = "Wayland",
@@ -276,6 +303,8 @@ struct LG_DisplayServerOps LGDS_Wayland =
   .getFullscreen       = waylandGetFullscreen,
   .minimize            = waylandMinimize,
 
+  .setHDRImageDescription = waylandHDRCallback,
+
   .cbInit    = waylandCBInit,
   .cbNotice  = waylandCBNotice,
   .cbRelease = waylandCBRelease,

client/displayservers/Wayland/wayland.h

@@ -49,6 +49,7 @@
 #include "wayland-xdg-activation-v1-client-protocol.h"
 #include "wayland-fractional-scale-v1-client-protocol.h"
 #include "wayland-content-type-v1-client-protocol.h"
+#include "wayland-color-management-v1-client-protocol.h"
 
 #include "scale.h"
 
@@ -120,7 +121,8 @@ struct WaylandDSState
 
 #ifdef ENABLE_OPENGL
   EGLDisplay glDisplay;
-  EGLConfig glConfig;
+  EGLConfig  glConfig;    // primary config (best bit depth probed)
+  EGLConfig  glConfigSDR; // fallback 8-bit SDR config
   EGLSurface glSurface;
 #endif
 
@@ -180,6 +182,42 @@ struct WaylandDSState
   struct wp_content_type_manager_v1 * contentTypeManager;
   struct wp_content_type_v1 * contentType;
 
+  // Color management (HDR)
+  struct wp_color_manager_v1                    * colorManager;
+  struct wp_color_management_surface_v1         * colorSurface;
+  struct wp_image_description_v1                * hdrImageDesc;
+  struct wp_image_description_creator_params_v1 * hdrImageCreator;
+
+  // Set to true when an HDR image description is active on the surface
+  bool hdrActive;
+
+  // wp_color_manager_v1 feature advertisement tracking.
+  // Set to true after the done event for the color-manager has been received
+  // and all compositor capabilities have been recorded.
+  bool cmFeaturesDone;
+  bool cmHasParametric;
+  bool cmHasLuminances;
+  bool cmHasMasteringPrimaries;
+  bool cmHasTFSt2084PQ;
+  bool cmHasTFExtLinear;
+  bool cmHasPrimariesBT2020;
+  bool cmHasPrimariesSRGB;
+  bool cmHasPerceptualIntent;
+  bool cmCanDoHDR;       // true if compositor supports features needed for HDR
+
+  // Pending HDR format to apply (set by frame thread, applied in swap buffers).
+  // pendingHDRApply and pendingHDRClear are accessed from multiple threads
+  // without a lock, so they must be atomic.
+  _Atomic(bool) pendingHDRApply;
+  _Atomic(bool) pendingHDRClear;
+  bool          pendingHDRPQ;
+  uint16_t      pendingHDRDisplayPrimary[3][2];
+  uint16_t      pendingHDRWhitePoint[2];
+  uint32_t      pendingHDRMaxDisplayLuminance;
+  uint32_t      pendingHDRMinDisplayLuminance;
+  uint32_t      pendingHDRMaxCLL;
+  uint32_t      pendingHDRMaxFALL;
+
   LGEvent * frameEvent;
 
   struct wl_list poll; // WaylandPoll::link
@@ -262,6 +300,24 @@ void waylandGLSetSwapInterval(int interval);
 void waylandGLSwapBuffers(void);
 #endif
 
+// HDR color management (Wayland color-management-v1)
+bool waylandColorMgmtInit(void);
+void waylandColorMgmtFree(void);
+void waylandSetHDRImageDescription(const uint16_t displayPrimary[3][2],
+    const uint16_t whitePoint[2], uint32_t maxDisplayLuminance,
+    uint32_t minDisplayLuminance, uint32_t maxCLL, uint32_t maxFALL,
+    bool hdrPQ);
+void waylandClearHDRImageDescription(void);
+
+// Queue HDR change from any thread (applied in waylandEGLSwapBuffers).
+// Returns true if the request was queued, false if HDR is not available
+// (no color manager, missing features, or unsupported TF/primaries).
+bool waylandRequestHDR(const uint16_t displayPrimary[3][2],
+    const uint16_t whitePoint[2], uint32_t maxDisplayLuminance,
+    uint32_t minDisplayLuminance, uint32_t maxCLL, uint32_t maxFALL,
+    bool hdrPQ);
+void waylandRequestClearHDR(void);
+
 // idle module
 bool waylandIdleInit(void);
 void waylandIdleFree(void);

client/include/app.h

@@ -72,6 +72,13 @@ void app_setFullscreen(bool fs);
 bool app_getFullscreen(void);
 bool app_getProp(LG_DSProperty prop, void * ret);
 
+/**
+ * Returns true if the last call to setHDRImageDescription() failed.
+ * When this returns true, the renderer should fall back to software
+ * tone-mapping even on a compositor that reports LG_DS_NATIVE_HDR.
+ */
+bool app_getHDRDescFailed(void);
+
 #ifdef ENABLE_EGL
 EGLDisplay app_getEGLDisplay(void);
 EGLNativeWindowType app_getEGLNativeWindow(void);

client/include/interface/displayserver.h

@@ -53,6 +53,14 @@ typedef enum LG_DSProperty
    * return data type: bool
    */
   LG_DS_WARP_SUPPORT,
+
+  /**
+   * returns true if the display server supports native HDR via
+   * setHDRImageDescription (i.e., the compositor actually has the
+   * required color-management features to process HDR content).
+   * return data type: bool
+   */
+  LG_DS_NATIVE_HDR,
 }
 LG_DSProperty;
 
@@ -213,6 +221,13 @@ struct LG_DisplayServerOps
   void (*setFullscreen)(bool fs);
   void (*minimize)(void);
 
+  /* HDR color management - set display image description.
+   * Optional, if not supported set to NULL.
+   * Returns true on success, false if the description could not be applied
+   * (e.g., compositor doesn't support the required transfer function or
+   * primaries, or the image description creation failed). */
+  bool (*setHDRImageDescription)(const void * rendererFormat);
+
   /* clipboard support, optional, if not supported set to NULL */
   bool (*cbInit)(void);
   void (*cbNotice)(LG_ClipboardData type);

client/include/interface/renderer.h

@@ -84,6 +84,14 @@ typedef struct LG_RendererFormat
   unsigned int      pitch;   // scanline bytes (or compressed size)
   unsigned int      bpp;     // bits per pixel (zero if compressed)
   LG_RendererRotate rotate;  // guest rotation
+
+  // HDR static metadata (from KVMFRFrame, valid when hdr is true)
+  uint16_t hdrDisplayPrimary[3][2];
+  uint16_t hdrWhitePoint[2];
+  uint32_t hdrMaxDisplayLuminance;
+  uint32_t hdrMinDisplayLuminance;
+  uint32_t hdrMaxContentLightLevel;
+  uint32_t hdrMaxFrameAverageLightLevel;
 }
 LG_RendererFormat;
 

client/renderers/EGL/desktop.c

@@ -91,6 +91,7 @@ struct EGL_Desktop
 
   // map HDR content to SDR
   bool  mapHDRtoSDR;
+  bool  nativeHDR;
   int   peakLuminance;
   int   maxCLL;
 
@@ -548,7 +549,7 @@ bool egl_desktopRender(EGL_Desktop * desktop, unsigned int outputWidth,
     {
       .type        = EGL_UNIFORM_TYPE_1I,
       .location    = shader->uCBMode,
-      .f           = { desktop->cbMode }
+      .i           = { desktop->cbMode }
     },
     {
       .type        = EGL_UNIFORM_TYPE_1I,
@@ -558,7 +559,7 @@ bool egl_desktopRender(EGL_Desktop * desktop, unsigned int outputWidth,
     {
       .type        = EGL_UNIFORM_TYPE_1I,
       .location    = shader->uMapHDRtoSDR,
-      .i           = { desktop->mapHDRtoSDR }
+      .i           = { desktop->mapHDRtoSDR && !desktop->nativeHDR }
     },
     {
       .type        = EGL_UNIFORM_TYPE_1F,
@@ -568,7 +569,7 @@ bool egl_desktopRender(EGL_Desktop * desktop, unsigned int outputWidth,
     {
       .type        = EGL_UNIFORM_TYPE_1I,
       .location    = shader->uMapHDRPQ,
-      .f           = { desktop->hdrPQ }
+      .i           = { desktop->hdrPQ }
     }
   };
 
@@ -579,6 +580,11 @@ bool egl_desktopRender(EGL_Desktop * desktop, unsigned int outputWidth,
   return true;
 }
 
+void egl_desktopSetNativeHDR(EGL_Desktop * desktop, bool nativeHDR)
+{
+  desktop->nativeHDR = nativeHDR;
+}
+
 void egl_desktopSpiceConfigure(EGL_Desktop * desktop, int width, int height)
 {
   if (!desktop->spiceTexture)

client/renderers/EGL/desktop.h

@@ -42,6 +42,7 @@ bool egl_desktopInit(EGL * egl, EGL_Desktop ** desktop, EGLDisplay * display,
 void egl_desktopFree(EGL_Desktop ** desktop);
 
 void egl_desktopConfigUI(EGL_Desktop * desktop);
+void egl_desktopSetNativeHDR(EGL_Desktop * desktop, bool nativeHDR);
 bool egl_desktopSetup (EGL_Desktop * desktop, const LG_RendererFormat format);
 bool egl_desktopUpdate(EGL_Desktop * desktop, const FrameBuffer * frame, int dmaFd,
     const FrameDamageRect * damageRects, int damageRectsCount);

client/renderers/EGL/egl.c

@@ -121,6 +121,9 @@ struct Inst
 
   bool showSpice;
   int  spiceWidth, spiceHeight;
+
+  bool configSupportsHDR; // true if we probed FP16 or 10-bit EGL config
+  bool hdr;               // true if current frame format is HDR
 };
 
 static struct Option egl_options[] =
@@ -607,6 +610,26 @@ static bool egl_onFrameFormat(LG_Renderer * renderer, const LG_RendererFormat fo
     egl_cursorSetScale(this->cursor, scale);
   }
 
+  // Track HDR state and warn if HDR frames arrive without any HDR path
+  this->hdr = format.hdr;
+  if (format.hdr)
+  {
+    bool nativeHDR = false;
+    app_getProp(LG_DS_NATIVE_HDR, &nativeHDR);
+    if (!this->configSupportsHDR && !nativeHDR)
+      DEBUG_WARN("HDR frames being displayed on an 8-bit EGL surface "
+          "without a color-managed compositor; tones may be incorrect");
+  }
+
+  // If the display server supports native HDR (via setHDRImageDescription),
+  // disable software tone-mapping to avoid double tone-mapping.
+  // However, if the last call to setHDRImageDescription actually failed
+  // (e.g., compositor missing required primaries), keep tone-mapping on.
+  bool nativeHDR = false;
+  app_getProp(LG_DS_NATIVE_HDR, &nativeHDR);
+  egl_desktopSetNativeHDR(this->desktop,
+      format.hdr && nativeHDR && !app_getHDRDescFailed());
+
   egl_update_scale_type(this);
   egl_damageSetup(this->damage, format.frameWidth, format.frameHeight);
 
@@ -774,22 +797,51 @@ static bool egl_renderStartup(LG_Renderer * renderer, bool useDMA)
     }
   }
 
-  EGLint attr[] =
+  // Probe for best available color depth: FP16 → 10-bit → 8-bit
+  static const struct { EGLint r, g, b, a, depth; const char * desc; } configs[] =
   {
-    EGL_BUFFER_SIZE    , 30,
-    EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
-    EGL_SAMPLE_BUFFERS , maxSamples > 0 ? 1 : 0,
-    EGL_SAMPLES        , maxSamples,
-    EGL_NONE
+    { 16, 16, 16,  0, 48, "FP16 (RGBA16F)"  },
+    { 10, 10, 10,  2, 32, "10-bit (RGBA10)" },
+    {  8,  8,  8,  0, 24, "8-bit (RGBA8)"   },
   };
+  EGLint       num_config;
+  const char * configDesc = NULL;
+  int          chosen     = -1;
 
-  EGLint num_config;
-  if (!eglChooseConfig(this->display, attr, &this->configs, 1, &num_config))
+  for (int i = 0; i < (int)(sizeof(configs) / sizeof(configs[0])); ++i)
   {
-    DEBUG_ERROR("Failed to choose config (eglError: 0x%x)", eglGetError());
+    EGLint attr[] =
+    {
+      EGL_RED_SIZE        , configs[i].r,
+      EGL_GREEN_SIZE      , configs[i].g,
+      EGL_BLUE_SIZE       , configs[i].b,
+      EGL_ALPHA_SIZE      , configs[i].a,
+      EGL_BUFFER_SIZE     , configs[i].depth,
+      EGL_RENDERABLE_TYPE , EGL_OPENGL_ES2_BIT,
+      EGL_SAMPLE_BUFFERS  , maxSamples > 0 ? 1 : 0,
+      EGL_SAMPLES         , maxSamples,
+      EGL_NONE
+    };
+
+    if (eglChooseConfig(this->display, attr, &this->configs, 1, &num_config) &&
+        num_config > 0)
+    {
+      configDesc = configs[i].desc;
+      chosen     = i;
+      break;
+    }
+  }
+
+  if (chosen < 0)
+  {
+    DEBUG_ERROR("Failed to choose any EGL config");
     return false;
   }
 
+  this->configSupportsHDR = chosen <= 1; // FP16 or 10-bit
+  DEBUG_INFO("EGL config: %s%s", configDesc,
+      this->configSupportsHDR ? " (HDR capable)" : "");
+
   const EGLint surfattr[] =
   {
     EGL_RENDER_BUFFER, this->opt.doubleBuffer ? EGL_BACK_BUFFER : EGL_SINGLE_BUFFER,

client/src/app.c

@@ -618,6 +618,11 @@ bool app_getProp(LG_DSProperty prop, void * ret)
   return g_state.ds->getProp(prop, ret);
 }
 
+bool app_getHDRDescFailed(void)
+{
+  return atomic_load(&g_state.hdrDescFailed);
+}
+
 #ifdef ENABLE_EGL
 EGLDisplay app_getEGLDisplay(void)
 {

client/src/main.c

@@ -641,6 +641,25 @@ int main_frameThread(void * unused)
       lgrFormat.hdr          = frame->flags & FRAME_FLAG_HDR;
       lgrFormat.hdrPQ        = frame->flags & FRAME_FLAG_HDR_PQ;
 
+      if (lgrFormat.hdr)
+      {
+        memcpy(lgrFormat.hdrDisplayPrimary, frame->hdrDisplayPrimary, sizeof(lgrFormat.hdrDisplayPrimary));
+        memcpy(lgrFormat.hdrWhitePoint    , frame->hdrWhitePoint    , sizeof(lgrFormat.hdrWhitePoint    ));
+        lgrFormat.hdrMaxDisplayLuminance       = frame->hdrMaxDisplayLuminance;
+        lgrFormat.hdrMinDisplayLuminance       = frame->hdrMinDisplayLuminance;
+        lgrFormat.hdrMaxContentLightLevel      = frame->hdrMaxContentLightLevel;
+        lgrFormat.hdrMaxFrameAverageLightLevel = frame->hdrMaxFrameAverageLightLevel;
+      }
+      else
+      {
+        memset(lgrFormat.hdrDisplayPrimary, 0, sizeof(lgrFormat.hdrDisplayPrimary));
+        memset(lgrFormat.hdrWhitePoint    , 0, sizeof(lgrFormat.hdrWhitePoint    ));
+        lgrFormat.hdrMaxDisplayLuminance       = 0;
+        lgrFormat.hdrMinDisplayLuminance       = 0;
+        lgrFormat.hdrMaxContentLightLevel      = 0;
+        lgrFormat.hdrMaxFrameAverageLightLevel = 0;
+      }
+
       if (frame->flags & FRAME_FLAG_TRUNCATED)
       {
         const float needed =
@@ -728,6 +747,17 @@ int main_frameThread(void * unused)
       }
       LG_UNLOCK(g_state.lgrLock);
 
+      if (g_state.ds->setHDRImageDescription)
+      {
+        if (!g_state.ds->setHDRImageDescription(&lgrFormat))
+        {
+          DEBUG_WARN("Display server failed to apply HDR image description");
+          atomic_store(&g_state.hdrDescFailed, true);
+        }
+        else
+          atomic_store(&g_state.hdrDescFailed, false);
+      }
+
       g_state.srcSize.x = lgrFormat.screenWidth;
       g_state.srcSize.y = lgrFormat.screenHeight;
       g_state.haveSrcSize = true;

client/src/main.h

@@ -154,6 +154,11 @@ struct AppState
   enum MicDefaultState micDefaultState;
 
   int spiceHotX, spiceHotY;
+
+  // Set to true when setHDRImageDescription() returns false, indicating
+  // the display server could not apply the HDR image description.
+  // Checked by the renderer to fall back to software tone-mapping.
+  _Atomic(bool) hdrDescFailed;
 };
 
 struct AppParams

common/include/common/KVMFR.h

@@ -162,6 +162,15 @@ typedef struct KVMFRFrame
   uint32_t        damageRectsCount;   // the number of damage rectangles (zero for full-frame damage)
   FrameDamageRect damageRects[KVMFR_MAX_DAMAGE_RECTS];
   KVMFRFrameFlags flags;              // bit field combination of FRAME_FLAG_*
+
+  // HDR static metadata (valid when FRAME_FLAG_HDR is set)
+  // Display color primaries in 0.00002 units (SMPTE ST 2086 format)
+  uint16_t hdrDisplayPrimary[3][2];      // Rx,Ry, Gx,Gy, Bx,By
+  uint16_t hdrWhitePoint[2];             // Wx, Wy
+  uint32_t hdrMaxDisplayLuminance;       // Max mastering display luminance (0.0001 cd/m²)
+  uint32_t hdrMinDisplayLuminance;       // Min mastering display luminance (0.0001 cd/m²)
+  uint32_t hdrMaxContentLightLevel;      // MaxCLL (cd/m²)
+  uint32_t hdrMaxFrameAverageLightLevel; // MaxFALL (cd/m²)
 }
 KVMFRFrame;
 

gl-check

@@ -49,7 +49,7 @@ getCalls() {
   cat > "$tempdir/query" <<EOF
 set output print
 set bind-root false
-m callExpr(callee(functionDecl(matchesName("::$query")).bind("func")))
+m callExpr(callee(functionDecl(matchesName("::$query"), unless(isStatic())).bind("func")))
 EOF
 
   "${command[@]}" -exec "$CLANG_QUERY" -p "$BUILD_DIR/compile_commands.json" -f "$tempdir/query" {} + | \

idd/LGIdd/CIndirectDeviceContext.cpp

@@ -45,14 +45,14 @@ static const struct LGMPQueueConfig POINTER_QUEUE_CONFIG =
 
 static const UINT IDDCX_VERSION_1_10 = 0x1A00;
 
-#if defined(IDDCX_VERSION_MAJOR) && defined(IDDCX_VERSION_MINOR) && \
-  (IDDCX_VERSION_MAJOR > 1 || (IDDCX_VERSION_MAJOR == 1 && IDDCX_VERSION_MINOR >= 10))
+#ifdef HAS_IDDCX_110
 static inline IDDCX_WIRE_BITS_PER_COMPONENT GetWireBitsPerComponent(bool hdr)
 {
   IDDCX_WIRE_BITS_PER_COMPONENT bits = {};
   bits.Rgb = IDDCX_BITS_PER_COMPONENT_8;
   if (hdr)
-    bits.Rgb = (IDDCX_BITS_PER_COMPONENT)(bits.Rgb | IDDCX_BITS_PER_COMPONENT_10);
+    bits.Rgb = (IDDCX_BITS_PER_COMPONENT)(bits.Rgb |
+      IDDCX_BITS_PER_COMPONENT_10 | IDDCX_BITS_PER_COMPONENT_16);
   bits.YCbCr444 = IDDCX_BITS_PER_COMPONENT_NONE;
   bits.YCbCr422 = IDDCX_BITS_PER_COMPONENT_NONE;
   bits.YCbCr420 = IDDCX_BITS_PER_COMPONENT_NONE;
@@ -74,8 +74,7 @@ void CIndirectDeviceContext::QueryIddCxCapabilities()
 
   m_iddCxVersion = ver.IddCxVersion;
 
-#if defined(IDDCX_VERSION_MAJOR) && defined(IDDCX_VERSION_MINOR) && \
-  (IDDCX_VERSION_MAJOR > 1 || (IDDCX_VERSION_MAJOR == 1 && IDDCX_VERSION_MINOR >= 10))
+#ifdef HAS_IDDCX_110
   const bool hasIddCx110DDIs =
     !!IDD_IS_FUNCTION_AVAILABLE(IddCxSwapChainReleaseAndAcquireBuffer2) &&
     !!IDD_IS_FUNCTION_AVAILABLE(IddCxMonitorQueryHardwareCursor3) &&
@@ -126,8 +125,7 @@ void CIndirectDeviceContext::InitAdapter()
    * driver will not work. This behaviour is not documented by Microsoft.
    */
   caps.Flags = IDDCX_ADAPTER_FLAGS_USE_SMALLEST_MODE;
-#if defined(IDDCX_VERSION_MAJOR) && defined(IDDCX_VERSION_MINOR) && \
-  (IDDCX_VERSION_MAJOR > 1 || (IDDCX_VERSION_MAJOR == 1 && IDDCX_VERSION_MINOR >= 10))
+#ifdef HAS_IDDCX_110
   if (CanUseIddCx110DDIs())
     caps.Flags |= IDDCX_ADAPTER_FLAGS_CAN_PROCESS_FP16;
 #endif
@@ -188,7 +186,7 @@ void CIndirectDeviceContext::InitAdapter()
     dxgiAdapter->Release();
 
     if ((adapterDesc.VendorId == 0x1414 && adapterDesc.DeviceId == 0x008c) || // Microsoft Basic Render Driver
-        (adapterDesc.VendorId == 0x1b36 && adapterDesc.DeviceId == 0x000d) || // QXL      
+        (adapterDesc.VendorId == 0x1b36 && adapterDesc.DeviceId == 0x000d) || // QXL
         (adapterDesc.VendorId == 0x1234 && adapterDesc.DeviceId == 0x1111))   // QEMU Standard VGA
       continue;
 
@@ -200,7 +198,7 @@ void CIndirectDeviceContext::InitAdapter()
   factory->Release();
 
   auto * wrapper = WdfObjectGet_CIndirectDeviceContextWrapper(m_adapter);
-  wrapper->context = this;  
+  wrapper->context = this;
 }
 
 void CIndirectDeviceContext::FinishInit(UINT connectorIndex)
@@ -312,7 +310,7 @@ static inline void FillSignalInfo(DISPLAYCONFIG_VIDEO_SIGNAL_INFO & mode, DWORD
 
   mode.AdditionalSignalInfo.vSyncFreqDivider = monitorMode ? 0 : 1;
   mode.AdditionalSignalInfo.videoStandard    = 255;
-  
+
   mode.vSyncFreq.Numerator   = vsync;
   mode.vSyncFreq.Denominator = 1;
   mode.hSyncFreq.Numerator   = vsync * height;
@@ -389,8 +387,7 @@ NTSTATUS CIndirectDeviceContext::MonitorQueryTargetModes(
 }
 
 
-#if defined(IDDCX_VERSION_MAJOR) && defined(IDDCX_VERSION_MINOR) && \
-  (IDDCX_VERSION_MAJOR > 1 || (IDDCX_VERSION_MAJOR == 1 && IDDCX_VERSION_MINOR >= 10))
+#ifdef HAS_IDDCX_110
 NTSTATUS CIndirectDeviceContext::ParseMonitorDescription2(
   const IDARG_IN_PARSEMONITORDESCRIPTION2* inArgs,
   IDARG_OUT_PARSEMONITORDESCRIPTION* outArgs)
@@ -446,8 +443,7 @@ bool CIndirectDeviceContext::UpdateMonitorModes()
   if (!m_monitor)
     return false;
 
-#if defined(IDDCX_VERSION_MAJOR) && defined(IDDCX_VERSION_MINOR) && \
-  (IDDCX_VERSION_MAJOR > 1 || (IDDCX_VERSION_MAJOR == 1 && IDDCX_VERSION_MINOR >= 10))
+#ifdef HAS_IDDCX_110
   if (CanUseIddCx110DDIs())
   {
     IDDCX_TARGET_MODE2* modes = (IDDCX_TARGET_MODE2*)_malloca(
@@ -553,7 +549,7 @@ bool CIndirectDeviceContext::SetupLGMP(size_t alignSize)
     return true;
 
   m_alignSize = alignSize;
-  
+
   std::stringstream ss;
   {
     KVMFR kvmfr = {};
@@ -829,6 +825,35 @@ CIndirectDeviceContext::PreparedFrameBuffer CIndirectDeviceContext::PrepareFrame
     ++m_formatVer;
   }
 
+  // Detect HDR metadata changes that require a format version bump
+  // so the client knows to re-apply the HDR image description.
+  if (srcFormat.hdr)
+  {
+    if (!m_lastHDRActive ||
+        memcmp(m_lastHDRDisplayPrimary, srcFormat.displayPrimary, sizeof(m_lastHDRDisplayPrimary)) != 0 ||
+        memcmp(m_lastHDRWhitePoint    , srcFormat.whitePoint    , sizeof(m_lastHDRWhitePoint    )) != 0 ||
+        m_lastHDRMaxDisplayLuminance       != srcFormat.maxDisplayLuminance       ||
+        m_lastHDRMinDisplayLuminance       != srcFormat.minDisplayLuminance       ||
+        m_lastHDRMaxContentLightLevel      != srcFormat.maxContentLightLevel      ||
+        m_lastHDRMaxFrameAverageLightLevel != srcFormat.maxFrameAverageLightLevel)
+    {
+      ++m_formatVer;
+    }
+  }
+  else if (m_lastHDRActive)
+  {
+    // HDR was turned off
+    ++m_formatVer;
+  }
+
+  m_lastHDRActive = srcFormat.hdr;
+  memcpy(m_lastHDRDisplayPrimary, srcFormat.displayPrimary, sizeof(m_lastHDRDisplayPrimary));
+  memcpy(m_lastHDRWhitePoint    , srcFormat.whitePoint    , sizeof(m_lastHDRWhitePoint    ));
+  m_lastHDRMaxDisplayLuminance       = srcFormat.maxDisplayLuminance;
+  m_lastHDRMinDisplayLuminance       = srcFormat.minDisplayLuminance;
+  m_lastHDRMaxContentLightLevel      = srcFormat.maxContentLightLevel;
+  m_lastHDRMaxFrameAverageLightLevel = srcFormat.maxFrameAverageLightLevel;
+
   if (++m_frameIndex == LGMP_Q_FRAME_LEN)
     m_frameIndex = 0;
 
@@ -850,9 +875,6 @@ CIndirectDeviceContext::PreparedFrameBuffer CIndirectDeviceContext::PrepareFrame
     (dstFormat.hdr   ? FRAME_FLAG_HDR    : 0) |
     (dstFormat.hdrPQ ? FRAME_FLAG_HDR_PQ : 0);
 
-  if (dstFormat.format == FRAME_TYPE_RGBA16F)
-    flags |= FRAME_FLAG_HDR;
-
   if (maxRows < dstFormat.desc.Height)
     flags |= FRAME_FLAG_TRUNCATED;
 
@@ -870,6 +892,18 @@ CIndirectDeviceContext::PreparedFrameBuffer CIndirectDeviceContext::PrepareFrame
   fi->flags            = flags;
   fi->rotation         = FRAME_ROT_0;
   fi->type             = dstFormat.format;
+
+  // Populate HDR metadata if the frame is HDR
+  if (flags & FRAME_FLAG_HDR)
+  {
+    memcpy(fi->hdrDisplayPrimary, srcFormat.displayPrimary, sizeof(fi->hdrDisplayPrimary));
+    memcpy(fi->hdrWhitePoint    , srcFormat.whitePoint    , sizeof(fi->hdrWhitePoint));
+    fi->hdrMaxDisplayLuminance       = srcFormat.maxDisplayLuminance;
+    fi->hdrMinDisplayLuminance       = srcFormat.minDisplayLuminance;
+    fi->hdrMaxContentLightLevel      = srcFormat.maxContentLightLevel;
+    fi->hdrMaxFrameAverageLightLevel = srcFormat.maxFrameAverageLightLevel;
+  }
+
   fi->damageRectsCount = 0;
   if (nbDirtyRects <= ARRAYSIZE(fi->damageRects))
   {
@@ -931,7 +965,7 @@ void CIndirectDeviceContext::SendCursor(const IDARG_OUT_QUERY_HWCURSOR& info, co
   }
 
   KVMFRCursor * cursor = (KVMFRCursor *)lgmpHostMemPtr(mem);
-  
+
   m_cursorVisible = info.IsCursorVisible;
   uint32_t flags  = 0;
 
@@ -984,6 +1018,59 @@ void CIndirectDeviceContext::SendCursor(const IDARG_OUT_QUERY_HWCURSOR& info, co
   }
 }
 
+#ifdef HAS_IDDCX_110
+void CIndirectDeviceContext::SetHDRActive(const struct IDDCX_HDR10_METADATA * hdrMeta)
+{
+  AcquireSRWLockExclusive(&m_hdrLock);
+
+  if (!hdrMeta)
+  {
+    m_hdrActive = false;
+    ReleaseSRWLockExclusive(&m_hdrLock);
+    return;
+  }
+
+  m_hdrActive = true;
+
+  m_hdrDisplayPrimary[0][0] = hdrMeta->RedPrimary  [0];
+  m_hdrDisplayPrimary[0][1] = hdrMeta->RedPrimary  [1];
+  m_hdrDisplayPrimary[1][0] = hdrMeta->GreenPrimary[0];
+  m_hdrDisplayPrimary[1][1] = hdrMeta->GreenPrimary[1];
+  m_hdrDisplayPrimary[2][0] = hdrMeta->BluePrimary [0];
+  m_hdrDisplayPrimary[2][1] = hdrMeta->BluePrimary [1];
+  m_hdrWhitePoint    [0]    = hdrMeta->WhitePoint  [0];
+  m_hdrWhitePoint    [1]    = hdrMeta->WhitePoint  [1];
+
+  m_hdrMaxDisplayLuminance       = hdrMeta->MaxMasteringLuminance;
+  m_hdrMinDisplayLuminance       = hdrMeta->MinMasteringLuminance;
+  m_hdrMaxContentLightLevel      = hdrMeta->MaxContentLightLevel;
+  m_hdrMaxFrameAverageLightLevel = hdrMeta->MaxFrameAverageLightLevel;
+
+  ReleaseSRWLockExclusive(&m_hdrLock);
+}
+#endif
+
+bool CIndirectDeviceContext::GetHDRMetadata(D12FrameFormat & format) const
+{
+  AcquireSRWLockShared(&m_hdrLock);
+
+  if (!m_hdrActive)
+  {
+    ReleaseSRWLockShared(&m_hdrLock);
+    return false;
+  }
+
+  memcpy(format.displayPrimary, m_hdrDisplayPrimary, sizeof(format.displayPrimary));
+  memcpy(format.whitePoint    , m_hdrWhitePoint    , sizeof(format.whitePoint    ));
+  format.maxDisplayLuminance       = m_hdrMaxDisplayLuminance;
+  format.minDisplayLuminance       = m_hdrMinDisplayLuminance;
+  format.maxContentLightLevel      = m_hdrMaxContentLightLevel;
+  format.maxFrameAverageLightLevel = m_hdrMaxFrameAverageLightLevel;
+
+  ReleaseSRWLockShared(&m_hdrLock);
+  return true;
+}
+
 void CIndirectDeviceContext::ResendCursor() const
 {
   PLGMPMemory mem = m_pointerShape;
@@ -1010,4 +1097,4 @@ void CIndirectDeviceContext::ResendCursor() const
     DEBUG_ERROR("lgmpHostQueuePost Failed (Pointer): %s", lgmpStatusString(status));
     break;
   }
-}
+}

idd/LGIdd/CIndirectDeviceContext.h

@@ -35,6 +35,15 @@ extern "C" {
 }
 
 #include "common/KVMFR.h"
+
+// IddCx 1.10 HDR/WCG types are only visible when the WDK targets
+// (NTDDI >= 0x0A000005) *and* the build flags IDDCX_VERSION_MAJOR/MINOR are set to >= 1.10.
+#if defined(IDDCX_VERSION_MAJOR) && defined(IDDCX_VERSION_MINOR) && \
+  (IDDCX_VERSION_MAJOR > 1 || (IDDCX_VERSION_MAJOR == 1 && IDDCX_VERSION_MINOR >= 10)) && \
+  NTDDI_VERSION >= 0x0A000005
+  #define HAS_IDDCX_110
+#endif
+
 #define MAX_POINTER_SIZE (sizeof(KVMFRCursor) + (512 * 512 * 4))
 #define POINTER_SHAPE_BUFFERS 3
 
@@ -90,6 +99,27 @@ private:
   UINT m_iddCxVersion = 0;
   bool m_canProcessFP16 = false;
 
+  // HDR state from EvtIddCxMonitorSetDefaultHdrMetadata (IddCx 1.10+)
+  // Protected by m_hdrLock - accessed from both the IDD callback thread
+  // (SetHDRActive) and the swap-chain thread (PrepareFrameBuffer, GetHDRMetadata).
+  mutable SRWLOCK m_hdrLock               = SRWLOCK_INIT;
+  bool     m_hdrActive                    = false;
+  uint16_t m_hdrDisplayPrimary[3][2]      = {};
+  uint16_t m_hdrWhitePoint[2]             = {};
+  uint32_t m_hdrMaxDisplayLuminance       = 0;
+  uint32_t m_hdrMinDisplayLuminance       = 0;
+  uint32_t m_hdrMaxContentLightLevel      = 0;
+  uint32_t m_hdrMaxFrameAverageLightLevel = 0;
+
+  // Previous HDR metadata used to detect changes for formatVer bumps
+  uint16_t m_lastHDRDisplayPrimary[3][2]      = {};
+  uint16_t m_lastHDRWhitePoint[2]             = {};
+  uint32_t m_lastHDRMaxDisplayLuminance       = 0;
+  uint32_t m_lastHDRMinDisplayLuminance       = 0;
+  uint32_t m_lastHDRMaxContentLightLevel      = 0;
+  uint32_t m_lastHDRMaxFrameAverageLightLevel = 0;
+  bool     m_lastHDRActive                    = false;
+
   void QueryIddCxCapabilities();
   bool CanUseIddCx110DDIs() const { return m_canProcessFP16; }
 
@@ -130,8 +160,7 @@ public:
   NTSTATUS MonitorQueryTargetModes(
     const IDARG_IN_QUERYTARGETMODES* inArgs, IDARG_OUT_QUERYTARGETMODES* outArgs);
 
-#if defined(IDDCX_VERSION_MAJOR) && defined(IDDCX_VERSION_MINOR) && \
-  (IDDCX_VERSION_MAJOR > 1 || (IDDCX_VERSION_MAJOR == 1 && IDDCX_VERSION_MINOR >= 10))
+#ifdef HAS_IDDCX_110
   NTSTATUS ParseMonitorDescription2(
     const IDARG_IN_PARSEMONITORDESCRIPTION2* inArgs, IDARG_OUT_PARSEMONITORDESCRIPTION* outArgs);
   NTSTATUS MonitorQueryTargetModes2(
@@ -156,6 +185,22 @@ public:
 
   void SendCursor(const IDARG_OUT_QUERY_HWCURSOR & info, const BYTE * data);
 
+  // Tracks HDR state from EvtIddCxMonitorSetDefaultHdrMetadata
+  void SetHDRActive(const struct IDDCX_HDR10_METADATA * hdrMeta);
+
+  // Returns true if the display is currently in HDR mode
+  bool IsHDRActive() const
+  {
+    AcquireSRWLockShared(&m_hdrLock);
+    bool result = m_hdrActive;
+    ReleaseSRWLockShared(&m_hdrLock);
+    return result;
+  }
+
+  // Copies current HDR metadata into the provided D12FrameFormat.
+  // Returns true if HDR is active and metadata was copied.
+  bool GetHDRMetadata(D12FrameFormat & format) const;
+
   CIVSHMEM &GetIVSHMEM() { return m_ivshmem; }
 };
 
@@ -170,4 +215,4 @@ struct CIndirectDeviceContextWrapper
   }
 };
 
-WDF_DECLARE_CONTEXT_TYPE(CIndirectDeviceContextWrapper);
+WDF_DECLARE_CONTEXT_TYPE(CIndirectDeviceContextWrapper);

idd/LGIdd/CPlatformInfo.cpp

@@ -1,4 +1,4 @@
-/**
+/**
  * Looking Glass
  * Copyright © 2017-2026 The Looking Glass Authors
  * https://looking-glass.io
@@ -32,6 +32,60 @@ int         CPlatformInfo::m_cores   = 0;
 int         CPlatformInfo::m_procs   = 0;
 int         CPlatformInfo::m_sockets = 0;
 
+typedef PWSTR (WINAPI *PFN_BRANDING_FORMAT_STRING)(__in PCWSTR pstrFormat);
+
+inline bool brandingVersionString(std::string &output)
+{
+  HMODULE hWinBrand = LoadLibraryExA("winbrand.dll", nullptr, LOAD_LIBRARY_SEARCH_SYSTEM32);
+  if (!hWinBrand)
+    return false;
+
+  PFN_BRANDING_FORMAT_STRING BrandingFormatString =
+    (PFN_BRANDING_FORMAT_STRING) GetProcAddress(hWinBrand, "BrandingFormatString");
+
+  bool succeeded = false;
+
+  if (BrandingFormatString)
+  {
+    PWSTR pwstrOSName = BrandingFormatString(L"%WINDOWS_LONG%");
+
+    if (pwstrOSName)
+    {
+      int cbSize = WideCharToMultiByte(CP_UTF8, 0, pwstrOSName, -1, nullptr, 0, nullptr, nullptr);
+      output.resize(cbSize - 1);
+
+      if (WideCharToMultiByte(CP_UTF8, 0, pwstrOSName, -1, &output[0], cbSize, nullptr, nullptr))
+        succeeded = true;
+
+      GlobalFree((HGLOBAL)pwstrOSName);
+    }
+  }
+
+  FreeLibrary(hWinBrand);
+  return succeeded;
+}
+
+inline bool registryVersionString(std::string &output)
+{
+  DWORD bufferSize = 0;
+  LSTATUS status = RegGetValueA(HKEY_LOCAL_MACHINE,
+    "Software\\Microsoft\\Windows NT\\CurrentVersion", "ProductName",
+    RRF_RT_REG_SZ, nullptr, nullptr, &bufferSize);
+
+  if (status == ERROR_SUCCESS)
+  {
+    output.resize(bufferSize - 1);
+    status = RegGetValueA(HKEY_LOCAL_MACHINE,
+      "Software\\Microsoft\\Windows NT\\CurrentVersion", "ProductName",
+      RRF_RT_REG_SZ, nullptr, &output[0], &bufferSize);
+
+    if (status == ERROR_SUCCESS)
+      return true;
+  }
+
+  return false;
+}
+
 void CPlatformInfo::Init()
 {
   SYSTEM_INFO si;
@@ -46,26 +100,7 @@ void CPlatformInfo::Init()
   GetVersionExA(&osvi);
 #pragma warning(pop)
 
-  DWORD bufferSize = 0;
-  LSTATUS status = RegGetValueA(HKEY_LOCAL_MACHINE,
-    "Software\\Microsoft\\Windows NT\\CurrentVersion", "ProductName",
-    RRF_RT_REG_SZ, nullptr, nullptr, &bufferSize);
-  if (status == ERROR_SUCCESS)
-  {
-    m_productName.resize(bufferSize);
-    status = RegGetValueA(HKEY_LOCAL_MACHINE,
-      "Software\\Microsoft\\Windows NT\\CurrentVersion", "ProductName",
-      RRF_RT_REG_SZ, nullptr, &m_productName[0], &bufferSize);
-
-    if (status != ERROR_SUCCESS)
-    {
-      m_productName = "Unknown";
-      DEBUG_ERROR("Failed to read the ProductName");
-    }
-    else
-      m_productName.resize(bufferSize - 1); // remove the double null termination
-  }
-  else
+  if (!brandingVersionString(m_productName) && !registryVersionString(m_productName))
   {
     m_productName = "Windows " +
       std::to_string(osvi.dwMajorVersion) + "." +

idd/LGIdd/CPostProcessor.h

@@ -41,6 +41,19 @@ struct D12FrameFormat
   FrameType           format = FRAME_TYPE_INVALID;
   bool                hdr = false;
   bool                hdrPQ = false;
+
+  // HDR static metadata (SMPTE ST 2086)
+  // Display color primaries in 0.00002 units (xy coordinates)
+  uint16_t displayPrimary[3][2];
+  // White point in 0.00002 units
+  uint16_t whitePoint[2];
+  // Max display luminance in 0.0001 cd/m² units
+  uint32_t maxDisplayLuminance;
+  // Min display luminance in 0.0001 cd/m² units
+  uint32_t minDisplayLuminance;
+  // MaxCLL and MaxFALL in cd/m²
+  uint32_t maxContentLightLevel;
+  uint32_t maxFrameAverageLightLevel;
 };
 
 class CPostProcessEffect

idd/LGIdd/CSwapChainProcessor.cpp

@@ -145,8 +145,7 @@ void CSwapChainProcessor::SwapChainThreadCore()
     UINT dirtyRectCount = 0;
     ComPtr<IDXGIResource> surface;
 
-#if defined(IDDCX_VERSION_MAJOR) && defined(IDDCX_VERSION_MINOR) && \
-  (IDDCX_VERSION_MAJOR > 1 || (IDDCX_VERSION_MAJOR == 1 && IDDCX_VERSION_MINOR >= 10))
+#ifdef HAS_IDDCX_110
     if (m_devContext->CanProcessFP16())
     {
       IDARG_IN_RELEASEANDACQUIREBUFFER2 acquireIn = {};
@@ -366,8 +365,59 @@ bool CSwapChainProcessor::SwapChainNewFrame(ComPtr<IDXGIResource> acquiredBuffer
   srcFormat.width  = (unsigned)srcDesc.Width;
   srcFormat.height = srcDesc.Height;
   srcFormat.format = GetFrameType(srcDesc.Format);
-  srcFormat.hdr    = srcDesc.Format == DXGI_FORMAT_R16G16B16A16_FLOAT;
-  srcFormat.hdrPQ  = false;
+
+  // Only HDR-capable formats can carry HDR content.
+  // 8-bit formats (BGRA, RGBA) cannot represent HDR,
+  // even if IsHDRActive() is momentarily stale during mode switches.
+  if (srcDesc.Format != DXGI_FORMAT_R16G16B16A16_FLOAT &&
+      srcDesc.Format != DXGI_FORMAT_R10G10B10A2_UNORM)
+  {
+    srcFormat.hdr   = false;
+    srcFormat.hdrPQ = false;
+  }
+  else if (srcDesc.Format == DXGI_FORMAT_R16G16B16A16_FLOAT)
+  {
+    // FP16 is HDR content (scRGB / linear, not PQ-curve).
+    // FP16 always carries HDR color data regardless of OS HDR mode,
+    // but metadata (primaries, luminances) may be unavailable.
+    srcFormat.hdr   = true;
+    srcFormat.hdrPQ = false;
+    if (!m_devContext->GetHDRMetadata(srcFormat))
+    {
+      // No HDR metadata from the OS; provide reasonable defaults
+      // so downstream consumers have valid primaries and luminances.
+      // BT.709/sRGB primaries (in 0.00002 units):
+      srcFormat.displayPrimary[0][0] = 13250; // Rx
+      srcFormat.displayPrimary[0][1] = 34500; // Ry
+      srcFormat.displayPrimary[1][0] =  7500; // Gx
+      srcFormat.displayPrimary[1][1] = 30000; // Gy
+      srcFormat.displayPrimary[2][0] = 34000; // Bx
+      srcFormat.displayPrimary[2][1] = 16000; // By
+      // D65 white point (in 0.00002 units):
+      srcFormat.whitePoint[0] = 15635;
+      srcFormat.whitePoint[1] = 16450;
+      // 80 cd/m² display, 0.005 cd/m² black (in 0.0001 cd/m² units):
+      srcFormat.maxDisplayLuminance = 800000;
+      srcFormat.minDisplayLuminance = 50;
+      // Content light levels unknown:
+      srcFormat.maxContentLightLevel      = 0;
+      srcFormat.maxFrameAverageLightLevel = 0;
+    }
+  }
+  else if (m_devContext->CanProcessFP16() && m_devContext->IsHDRActive())
+  {
+    // Non-FP16 format (e.g., RGBA10) with OS HDR mode active.
+    // Windows applies the PQ (ST.2084) transfer function for non-FP16 HDR.
+    srcFormat.hdr   = true;
+    srcFormat.hdrPQ = true;
+
+    // Load HDR metadata; if none is available the frame is not HDR.
+    if (!m_devContext->GetHDRMetadata(srcFormat))
+    {
+      srcFormat.hdr   = false;
+      srcFormat.hdrPQ = false;
+    }
+  }
 
   bool postProcessFormatChanged = false;
   if (!m_postProcessor.Configure(srcFormat, &postProcessFormatChanged))
@@ -511,8 +561,7 @@ bool CSwapChainProcessor::QueryHWCursor()
 
   IDARG_OUT_QUERY_HWCURSOR out = {};
   NTSTATUS status;
-#if defined(IDDCX_VERSION_MAJOR) && defined(IDDCX_VERSION_MINOR) && \
-  (IDDCX_VERSION_MAJOR > 1 || (IDDCX_VERSION_MAJOR == 1 && IDDCX_VERSION_MINOR >= 10))
+#ifdef HAS_IDDCX_110
   if (m_devContext->CanProcessFP16())
   {
     IDARG_OUT_QUERY_HWCURSOR3 out3 = {};
@@ -588,4 +637,4 @@ void CSwapChainProcessor::CursorThread()
       return;
     }
   }
-}
+}

idd/LGIdd/Device.cpp

@@ -40,8 +40,7 @@ static const UINT IDDCX_VERSION_1_10 = 0x1A00;
 
 static bool LGIddCanUseIddCx110DDIs(UINT iddCxVersion)
 {
-#if defined(IDDCX_VERSION_MAJOR) && defined(IDDCX_VERSION_MINOR) && \
-  (IDDCX_VERSION_MAJOR > 1 || (IDDCX_VERSION_MAJOR == 1 && IDDCX_VERSION_MINOR >= 10))
+#ifdef HAS_IDDCX_110
   return iddCxVersion >= IDDCX_VERSION_1_10 &&
     !!IDD_IS_FUNCTION_AVAILABLE(IddCxSwapChainReleaseAndAcquireBuffer2) &&
     !!IDD_IS_FUNCTION_AVAILABLE(IddCxMonitorQueryHardwareCursor3) &&
@@ -61,7 +60,7 @@ static bool LGIddCanUseIddCx110DDIs(UINT iddCxVersion)
 NTSTATUS LGIddDeviceD0Entry(WDFDEVICE device, WDF_POWER_DEVICE_STATE previousState)
 {
   UNREFERENCED_PARAMETER(previousState);
-  
+
   auto * wrapper = WdfObjectGet_CIndirectDeviceContextWrapper(device);
   wrapper->context->InitAdapter();
 
@@ -92,7 +91,7 @@ static inline void FillSignalInfo(DISPLAYCONFIG_VIDEO_SIGNAL_INFO & mode, DWORD
 
   mode.AdditionalSignalInfo.vSyncFreqDivider = monitorMode ? 0 : 1;
   mode.AdditionalSignalInfo.videoStandard    = 255;
-  
+
   mode.vSyncFreq.Numerator   = vsync;
   mode.vSyncFreq.Denominator = 1;
   mode.hSyncFreq.Numerator   = vsync * height;
@@ -127,8 +126,7 @@ NTSTATUS LGIddMonitorQueryTargetModes(IDDCX_MONITOR monitor, const IDARG_IN_QUER
 }
 
 
-#if defined(IDDCX_VERSION_MAJOR) && defined(IDDCX_VERSION_MINOR) && \
-  (IDDCX_VERSION_MAJOR > 1 || (IDDCX_VERSION_MAJOR == 1 && IDDCX_VERSION_MINOR >= 10))
+#ifdef HAS_IDDCX_110
 NTSTATUS LGIddParseMonitorDescription2(const IDARG_IN_PARSEMONITORDESCRIPTION2* inArgs,
   IDARG_OUT_PARSEMONITORDESCRIPTION* outArgs)
 {
@@ -165,8 +163,11 @@ NTSTATUS LGIddAdapterCommitModes2(IDDCX_ADAPTER adapter, const IDARG_IN_COMMITMO
 NTSTATUS LGIddMonitorSetDefaultHdrMetadata(IDDCX_MONITOR monitor,
   const IDARG_IN_MONITOR_SET_DEFAULT_HDR_METADATA* inArgs)
 {
-  UNREFERENCED_PARAMETER(monitor);
-  UNREFERENCED_PARAMETER(inArgs);
+  auto* wrapper = WdfObjectGet_CIndirectMonitorContextWrapper(monitor);
+  auto* ctx     = wrapper->context->GetDeviceContext();
+
+  ctx->SetHDRActive(inArgs->Data.pHdr10);
+
   return STATUS_SUCCESS;
 }
 
@@ -228,8 +229,7 @@ NTSTATUS LGIddCreateDevice(_Inout_ PWDFDEVICE_INIT deviceInit)
   config.EvtIddCxMonitorAssignSwapChain            = LGIddMonitorAssignSwapChain;
   config.EvtIddCxMonitorUnassignSwapChain          = LGIddMonitorUnassignSwapChain;
 
-#if defined(IDDCX_VERSION_MAJOR) && defined(IDDCX_VERSION_MINOR) && \
-  (IDDCX_VERSION_MAJOR > 1 || (IDDCX_VERSION_MAJOR == 1 && IDDCX_VERSION_MINOR >= 10))
+#ifdef HAS_IDDCX_110
   if (hasIddCx110DDIs)
   {
     config.EvtIddCxParseMonitorDescription2      = LGIddParseMonitorDescription2;

idd/LGIdd/effect/CHDR16to10Effect.cpp

@@ -36,14 +36,24 @@ bool CHDR16to10Effect::Init(const ComPtr<ID3D12Device3>& device)
   const char * shader =
     "cbuffer Constants : register(b0)\n"
     "{\n"
-    "  float SDRWhiteLevel;\n"
+    "  float ReferenceWhiteNits;\n"
     "};\n"
     "Texture2D<float4> src : register(t0);\n"
     "RWTexture2D<float4> dst : register(u0);\n"
+    "static const float PQ_m1 = 0.1593017578125;\n"
+    "static const float PQ_m2 = 78.84375;\n"
+    "static const float PQ_c1 = 0.8359375;\n"
+    "static const float PQ_c2 = 18.8515625;\n"
+    "static const float PQ_c3 = 18.6875;\n"
     "[numthreads(" POST_PROCESS_THREADS_STR ", " POST_PROCESS_THREADS_STR ", 1)]\n"
     "void main(uint3 dt : SV_DispatchThreadID)\n"
     "{\n"
-    "  dst[dt.xy] = float4(src[dt.xy].rgb * SDRWhiteLevel, src[dt.xy].a);\n"
+    "  float3 linearValue = src[dt.xy].rgb * ReferenceWhiteNits;\n"
+    "  // scRGB to PQ (ST.2084)\n"
+    "  float3 Y = linearValue / 10000.0;\n"
+    "  float3 Ym1 = pow(max(Y, 0.0), PQ_m1);\n"
+    "  float3 pq = pow((PQ_c1 + PQ_c2 * Ym1) / (1.0 + PQ_c3 * Ym1), PQ_m2);\n"
+    "  dst[dt.xy] = float4(pq, src[dt.xy].a);\n"
     "}\n";
 
   if (!InitCompute(device, ranges, ARRAYSIZE(ranges), nullptr, 0, shader))
@@ -99,10 +109,20 @@ PostProcessStatus CHDR16to10Effect::SetFormat(
   m_threadsX = ((unsigned)desc.Width  + (Threads - 1)) / Threads;
   m_threadsY = ((unsigned)desc.Height + (Threads - 1)) / Threads;
 
-  dst.desc         = desc;
+  dst.desc   = desc;
   dst.format = FRAME_TYPE_RGBA10;
-  dst.hdr          = true;
-  dst.hdrPQ        = false;
+  dst.hdr    = true;
+  dst.hdrPQ  = true;
+
+  // Explicitly propagate HDR static metadata so it survives post-processing.
+  // Do not rely on the caller's copy semantics in CPostProcessor::Configure().
+  memcpy(dst.displayPrimary, src.displayPrimary, sizeof(dst.displayPrimary));
+  memcpy(dst.whitePoint    , src.whitePoint    , sizeof(dst.whitePoint    ));
+  dst.maxDisplayLuminance       = src.maxDisplayLuminance;
+  dst.minDisplayLuminance       = src.minDisplayLuminance;
+  dst.maxContentLightLevel      = src.maxContentLightLevel;
+  dst.maxFrameAverageLightLevel = src.maxFrameAverageLightLevel;
+
   return PostProcessStatus::SUCCESS;
 }
 

idd/LGIdd/effect/CHDR16to10Effect.h

@@ -18,8 +18,8 @@ class CHDR16to10Effect : public CComputeEffect
 private:
   struct Consts
   {
-    float SDRWhiteLevel;
-  } m_consts = { 1.0f };
+    float ReferenceWhiteNits; // scRGB reference white in nits (BT.2408 recommends 203)
+  } m_consts = { 203.0f };
   ComPtr<ID3D12Resource> m_constBuffer;
 
 public:

obs/lg.c

@@ -96,6 +96,7 @@ typedef struct
   uint32_t             linesize;
 
   bool                 hideMouse;
+  bool                 hdr;
 #if LIBOBS_API_MAJOR_VER >= 27
   bool                 dmabuf;
   bool                 dmabufTested;
@@ -619,6 +620,7 @@ static void lgFormatInit(LGPlugin * this, const KVMFRFrame * frame,
 
   this->dataWidth = frame->dataWidth;
   this->unpack    = false;
+  this->hdr       = frame->flags & FRAME_FLAG_HDR;
 
   this->bpp = 4;
   switch(this->type)
@@ -643,7 +645,7 @@ static void lgFormatInit(LGPlugin * this, const KVMFRFrame * frame,
       this->format     = GS_R10G10B10A2;
       this->drmFormat  = DRM_FORMAT_BGRA1010102;
 #if LIBOBS_API_MAJOR_VER >= 28
-      this->colorSpace = GS_CS_709_SCRGB;
+      this->colorSpace = this->hdr ? GS_CS_709_SCRGB : GS_CS_SRGB;
 #endif
       break;