From 72c6f529098b8069d03a4b2db9f1c34a25bca79c Mon Sep 17 00:00:00 2001
From: Brian Popow <popow@gmx.de>
Date: Sat, 4 Dec 2021 18:23:58 +0100
Subject: [PATCH 1/2] Allocate clean buffer in AnalyzeEntropy

---
 src/ImageSharp/Formats/Webp/Lossless/Vp8LEncoder.cs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/ImageSharp/Formats/Webp/Lossless/Vp8LEncoder.cs b/src/ImageSharp/Formats/Webp/Lossless/Vp8LEncoder.cs
index adabd0ac3..7769a0a6c 100644
--- a/src/ImageSharp/Formats/Webp/Lossless/Vp8LEncoder.cs
+++ b/src/ImageSharp/Formats/Webp/Lossless/Vp8LEncoder.cs
@@ -192,7 +192,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
         public bool UseCrossColorTransform { get; set; }
 
         /// <summary>
-        /// Gets or sets a value indicating whether to use the substract green transform.
+        /// Gets or sets a value indicating whether to use the subtract green transform.
         /// </summary>
         public bool UseSubtractGreenTransform { get; set; }
 
@@ -1049,7 +1049,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
                 return EntropyIx.Palette;
             }
 
-            using IMemoryOwner<uint> histoBuffer = this.memoryAllocator.Allocate<uint>((int)HistoIx.HistoTotal * 256);
+            using IMemoryOwner<uint> histoBuffer = this.memoryAllocator.Allocate<uint>((int)HistoIx.HistoTotal * 256, AllocationOptions.Clean);
             Span<uint> histo = histoBuffer.Memory.Span;
             uint pixPrev = bgra[0]; // Skip the first pixel.
             ReadOnlySpan<uint> prevRow = null;

From 3780ca78e0f6567e94ccecd8ab2856fca362ec21 Mon Sep 17 00:00:00 2001
From: Brian Popow <popow@gmx.de>
Date: Sat, 4 Dec 2021 19:54:49 +0100
Subject: [PATCH 2/2] Add lossless encode test which checks the expected bytes
 count of the encoded file

---
 .../Formats/WebP/WebpEncoderTests.cs           | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/tests/ImageSharp.Tests/Formats/WebP/WebpEncoderTests.cs b/tests/ImageSharp.Tests/Formats/WebP/WebpEncoderTests.cs
index 70cc487bf..ec0040a46 100644
--- a/tests/ImageSharp.Tests/Formats/WebP/WebpEncoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/WebP/WebpEncoderTests.cs
@@ -101,6 +101,24 @@ namespace SixLabors.ImageSharp.Tests.Formats.Webp
             image.VerifyEncoder(provider, "webp", testOutputDetails, encoder);
         }
 
+        [Theory]
+        [WithFile(Lossy.NoFilter06, PixelTypes.Rgba32, 15114)]
+        public void Encode_Lossless_WithBestQuality_HasExpectedSize<TPixel>(TestImageProvider<TPixel> provider, int expectedBytes)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            var encoder = new WebpEncoder()
+            {
+                FileFormat = WebpFileFormatType.Lossless,
+                Method = WebpEncodingMethod.BestQuality
+            };
+
+            using Image<TPixel> image = provider.GetImage();
+            using var memoryStream = new MemoryStream();
+            image.Save(memoryStream, encoder);
+
+            Assert.Equal(memoryStream.Length, expectedBytes);
+        }
+
         [Theory]
         [WithFile(RgbTestPattern100x100, PixelTypes.Rgba32, 85)]
         [WithFile(RgbTestPattern100x100, PixelTypes.Rgba32, 60)]