From a924483dc59077eaf41401a392597aea8c7dd222 Mon Sep 17 00:00:00 2001
From: Filoppi <filippotarpini@hotmail.it>
Date: Wed, 28 Jun 2023 02:30:03 +0300
Subject: [PATCH 1/2] Add AutoHDR post process shader

---
 Data/Sys/Shaders/AutoHDR.glsl | 64 +++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)
 create mode 100644 Data/Sys/Shaders/AutoHDR.glsl

diff --git a/Data/Sys/Shaders/AutoHDR.glsl b/Data/Sys/Shaders/AutoHDR.glsl
new file mode 100644
index 000000000000..6226d70d7c2d
--- /dev/null
+++ b/Data/Sys/Shaders/AutoHDR.glsl
@@ -0,0 +1,64 @@
+// Based on https://github.com/Filoppi/PumboAutoHDR
+
+/*
+[configuration]
+
+[OptionRangeFloat]
+GUIName = HDR Display Max Nits
+OptionName = HDR_DISPLAY_MAX_NITS
+MinValue = 80
+MaxValue = 2000
+StepAmount = 1
+DefaultValue = 400
+
+[OptionRangeFloat]
+GUIName = Shoulder Start Alpha
+OptionName = AUTO_HDR_SHOULDER_START_ALPHA
+MinValue = 0
+MaxValue = 1
+StepAmount = 0.01
+DefaultValue = 0
+
+[OptionRangeFloat]
+GUIName = Shoulder Pow
+OptionName = AUTO_HDR_SHOULDER_POW
+MinValue = 1
+MaxValue = 10
+StepAmount = 0.05
+DefaultValue = 2.5
+
+[/configuration]
+*/
+
+void main()
+{
+	float4 color = Sample();
+
+	// Nothing to do here, we are in SDR
+	if (!OptionEnabled(hdr_output) || !OptionEnabled(linear_space_output))
+	{
+		SetOutput(color);
+		return;
+	}
+
+	const float hdr_paper_white = hdr_paper_white_nits / hdr_sdr_white_nits;
+
+	// Restore the original SDR (0-1) brightness (we might or might not restore it later)
+	color.rgb /= hdr_paper_white;
+
+	// Find the color average
+	float sdr_ratio = (color.r + color.g + color.b) / 3.0;
+
+	const float auto_hdr_max_white = max(HDR_DISPLAY_MAX_NITS / (hdr_paper_white_nits / hdr_sdr_white_nits), hdr_sdr_white_nits) / hdr_sdr_white_nits;
+	if (sdr_ratio > AUTO_HDR_SHOULDER_START_ALPHA && AUTO_HDR_SHOULDER_START_ALPHA < 1.0)
+	{
+		const float auto_hdr_shoulder_ratio = 1.0 - (max(1.0 - sdr_ratio, 0.0) / (1.0 - AUTO_HDR_SHOULDER_START_ALPHA));
+		const float auto_hdr_extra_ratio = pow(auto_hdr_shoulder_ratio, AUTO_HDR_SHOULDER_POW) * (auto_hdr_max_white - 1.0);
+		const float auto_hdr_total_ratio = sdr_ratio + auto_hdr_extra_ratio;
+		color.rgb *= auto_hdr_total_ratio / sdr_ratio;
+	}
+
+	color.rgb *= hdr_paper_white;
+
+	SetOutput(color);
+}
\ No newline at end of file

From bfb90b7eeca2b4991f8ff2cf778090cabb84a481 Mon Sep 17 00:00:00 2001
From: Filoppi <filippotarpini@hotmail.it>
Date: Wed, 28 Jun 2023 02:31:14 +0300
Subject: [PATCH 2/2] Video: increase the max HDR brightness multiplier to a
 more appropriate value (400 nits can be too dark in a bright room)

---
 Source/Core/Core/Config/GraphicsSettings.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Source/Core/Core/Config/GraphicsSettings.h b/Source/Core/Core/Config/GraphicsSettings.h
index e24d47a39bb7..009b219136b3 100644
--- a/Source/Core/Core/Config/GraphicsSettings.h
+++ b/Source/Core/Core/Config/GraphicsSettings.h
@@ -117,7 +117,7 @@ static constexpr float GFX_CC_DISPLAY_GAMMA_MIN = 2.2f;
 static constexpr float GFX_CC_DISPLAY_GAMMA_MAX = 2.4f;
 
 static constexpr float GFX_CC_HDR_PAPER_WHITE_NITS_MIN = 80.f;
-static constexpr float GFX_CC_HDR_PAPER_WHITE_NITS_MAX = 400.f;
+static constexpr float GFX_CC_HDR_PAPER_WHITE_NITS_MAX = 500.f;
 
 extern const Info<bool> GFX_CC_CORRECT_COLOR_SPACE;
 extern const Info<ColorCorrectionRegion> GFX_CC_GAME_COLOR_SPACE;