From 1e777f595d99ce685a8dc6945a609fc2f9b4a476 Mon Sep 17 00:00:00 2001
From: Anton Firszov <antonfir@gmail.com>
Date: Thu, 22 Feb 2018 18:26:01 +0100
Subject: [PATCH] fixed JpegEncoderTests

---
 .../Formats/Jpg/JpegEncoderTests.cs           | 28 ++++++++++++-------
 tests/Images/External                         |  2 +-
 2 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/tests/ImageSharp.Tests/Formats/Jpg/JpegEncoderTests.cs b/tests/ImageSharp.Tests/Formats/Jpg/JpegEncoderTests.cs
index 10657ea78f..cc030bbf7c 100644
--- a/tests/ImageSharp.Tests/Formats/Jpg/JpegEncoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Jpg/JpegEncoderTests.cs
@@ -15,6 +15,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Jpg
     using SixLabors.ImageSharp.PixelFormats;
     using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison;
     using SixLabors.ImageSharp.Tests.TestUtilities.ReferenceCodecs;
+    using SixLabors.Primitives;
 
     using Xunit;
     using Xunit.Abstractions;
@@ -55,20 +56,27 @@ namespace SixLabors.ImageSharp.Tests.Formats.Jpg
             TestJpegEncoderCore(provider, subsample, quality);
         }
 
-        private static ImageComparer GetComparer(int quality)
+        /// <summary>
+        /// Anton's SUPER-SCIENTIFIC tolerance threshold calculation
+        /// </summary>
+        private static ImageComparer GetComparer(int quality, JpegSubsample subsample)
         {
-            if (quality > 90)
-            {
-                return ImageComparer.Tolerant(0.0005f / 100);
-            }
-            else if (quality > 50)
+            float tolerance = 0.015f; // ~1.5%
+
+            if (quality < 50)
             {
-                return ImageComparer.Tolerant(0.005f / 100);
+                tolerance *= 10f;
             }
-            else
+            else if (quality < 75 || subsample == JpegSubsample.Ratio420)
             {
-                return ImageComparer.Tolerant(0.01f / 100);
+                tolerance *= 5f;
+                if (subsample == JpegSubsample.Ratio420)
+                {
+                    tolerance *= 2f;
+                }
             }
+
+            return ImageComparer.Tolerant(tolerance);
         }
 
         private static void TestJpegEncoderCore<TPixel>(
@@ -88,7 +96,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Jpg
                                       Quality = quality
                                   };
                 string info = $"{subsample}-Q{quality}";
-                ImageComparer comparer = GetComparer(quality);
+                ImageComparer comparer = GetComparer(quality, subsample);
 
                 // Does DebugSave & load reference CompareToReferenceInput():
                 image.VerifyEncoder(provider, "jpeg", info, encoder, comparer, referenceImageExtension: "png");
diff --git a/tests/Images/External b/tests/Images/External
index d9c7d37074..20f83891ce 160000
--- a/tests/Images/External
+++ b/tests/Images/External
@@ -1 +1 @@
-Subproject commit d9c7d37074e112eabeccdde6381286f69b01b8b1
+Subproject commit 20f83891ce75597486f5532010a8c5dea1419a4d