Optimize and fix deduper

src/ImageSharp/Formats/AnimationUtilities.cs

@@ -25,26 +25,31 @@ internal static class AnimationUtilities
     /// <param name="configuration">The configuration.</param>
     /// <param name="previousFrame">The previous frame if present.</param>
     /// <param name="currentFrame">The current frame.</param>
+    /// <param name="nextFrame">The next frame if present.</param>
     /// <param name="resultFrame">The resultant output.</param>
     /// <param name="replacement">The value to use when replacing duplicate pixels.</param>
+    /// <param name="blend">Whether the resultant frame represents an animation blend.</param>
     /// <param name="clampingMode">The clamping bound to apply when calculating difference bounds.</param>
     /// <returns>The <see cref="ValueTuple{Boolean, Rectangle}"/> representing the operation result.</returns>
     public static (bool Difference, Rectangle Bounds) DeDuplicatePixels<TPixel>(
         Configuration configuration,
         ImageFrame<TPixel>? previousFrame,
         ImageFrame<TPixel> currentFrame,
+        ImageFrame<TPixel>? nextFrame,
         ImageFrame<TPixel> resultFrame,
-        Vector4 replacement,
+        Color replacement,
+        bool blend,
         ClampingMode clampingMode = ClampingMode.None)
         where TPixel : unmanaged, IPixel<TPixel>
     {
-        // TODO: This would be faster (but more complicated to find diff bounds) if we operated on Rgba32.
-        // If someone wants to do that, they have my unlimited thanks.
         MemoryAllocator memoryAllocator = configuration.MemoryAllocator;
-        IMemoryOwner<Vector4> buffers = memoryAllocator.Allocate<Vector4>(currentFrame.Width * 3, AllocationOptions.Clean);
+        IMemoryOwner<Rgba32> buffers = memoryAllocator.Allocate<Rgba32>(currentFrame.Width * 4, AllocationOptions.Clean);
-        Span<Vector4> previous = buffers.GetSpan()[..currentFrame.Width];
+        Span<Rgba32> previous = buffers.GetSpan()[..currentFrame.Width];
-        Span<Vector4> current = buffers.GetSpan().Slice(currentFrame.Width, currentFrame.Width);
+        Span<Rgba32> current = buffers.GetSpan().Slice(currentFrame.Width, currentFrame.Width);
-        Span<Vector4> result = buffers.GetSpan()[(currentFrame.Width * 2)..];
+        Span<Rgba32> next = buffers.GetSpan().Slice(currentFrame.Width * 2, currentFrame.Width);
+        Span<Rgba32> result = buffers.GetSpan()[(currentFrame.Width * 3)..];
+
+        Rgba32 bg = replacement;
 
         int top = int.MinValue;
         int bottom = int.MaxValue;
@@ -56,70 +61,90 @@ internal static class AnimationUtilities
         {
             if (previousFrame != null)
             {
-                PixelOperations<TPixel>.Instance.ToVector4(configuration, previousFrame.DangerousGetPixelRowMemory(y).Span, previous, PixelConversionModifiers.Scale);
+                PixelOperations<TPixel>.Instance.ToRgba32(configuration, previousFrame.DangerousGetPixelRowMemory(y).Span, previous);
             }
 
-            PixelOperations<TPixel>.Instance.ToVector4(configuration, currentFrame.DangerousGetPixelRowMemory(y).Span, current, PixelConversionModifiers.Scale);
+            PixelOperations<TPixel>.Instance.ToRgba32(configuration, currentFrame.DangerousGetPixelRowMemory(y).Span, current);
-
-            ref Vector256<float> previousBase = ref Unsafe.As<Vector4, Vector256<float>>(ref MemoryMarshal.GetReference(previous));
-            ref Vector256<float> currentBase = ref Unsafe.As<Vector4, Vector256<float>>(ref MemoryMarshal.GetReference(current));
-            ref Vector256<float> resultBase = ref Unsafe.As<Vector4, Vector256<float>>(ref MemoryMarshal.GetReference(result));
 
-            Vector256<float> replacement256 = Vector256.Create(replacement.X, replacement.Y, replacement.Z, replacement.W, replacement.X, replacement.Y, replacement.Z, replacement.W);
+            if (nextFrame != null)
+            {
+                PixelOperations<TPixel>.Instance.ToRgba32(configuration, nextFrame.DangerousGetPixelRowMemory(y).Span, next);
+            }
 
-            int size = Unsafe.SizeOf<Vector4>();
+            ref Vector256<byte> previousBase = ref Unsafe.As<Rgba32, Vector256<byte>>(ref MemoryMarshal.GetReference(previous));
+            ref Vector256<byte> currentBase = ref Unsafe.As<Rgba32, Vector256<byte>>(ref MemoryMarshal.GetReference(current));
+            ref Vector256<byte> nextBase = ref Unsafe.As<Rgba32, Vector256<byte>>(ref MemoryMarshal.GetReference(next));
+            ref Vector256<byte> resultBase = ref Unsafe.As<Rgba32, Vector256<byte>>(ref MemoryMarshal.GetReference(result));
 
-            bool hasRowDiff = false;
             int i = 0;
             uint x = 0;
+            bool hasRowDiff = false;
             int length = current.Length;
             int remaining = current.Length;
 
-            while (Avx2.IsSupported && remaining >= 2)
+            if (Avx2.IsSupported && remaining >= 8)
             {
-                Vector256<float> p = Unsafe.Add(ref previousBase, x);
+                Vector256<uint> r256 = previousFrame != null ? Vector256.Create(bg.PackedValue) : Vector256<uint>.Zero;
-                Vector256<float> c = Unsafe.Add(ref currentBase, x);
+                Vector256<uint> vmb256 = Vector256<uint>.Zero;
-
+                if (blend)
-                // Compare the previous and current pixels
-                Vector256<int> mask = Avx2.CompareEqual(p.AsInt32(), c.AsInt32());
-                mask = Avx2.CompareEqual(mask.AsInt64(), Vector256<long>.AllBitsSet).AsInt32();
-                mask = Avx2.And(mask, Avx2.Shuffle(mask, 0b_01_00_11_10)).AsInt32();
-
-                Vector256<int> neq = Avx2.Xor(mask.AsInt64(), Vector256<long>.AllBitsSet).AsInt32();
-                int m = Avx2.MoveMask(neq.AsByte());
-                if (m != 0)
                 {
-                    // If is diff is found, the left side is marked by the min of previously found left side and the start position.
+                    vmb256 = Avx2.CompareEqual(vmb256, vmb256);
-                    // The right is the max of the previously found right side and the end position.
-                    int start = i + (BitOperations.TrailingZeroCount(m) / size);
-                    int end = i + (2 - (BitOperations.LeadingZeroCount((uint)m) / size));
-                    left = Math.Min(left, start);
-                    right = Math.Max(right, end);
-                    hasRowDiff = true;
-                    hasDiff = true;
                 }
 
-                // Replace the pixel value with the replacement if the full pixel is matched.
+                while (remaining >= 8)
-                Vector256<float> r = Avx.BlendVariable(c, replacement256, mask.AsSingle());
+                {
-                Unsafe.Add(ref resultBase, x) = r;
+                    Vector256<uint> p = Unsafe.Add(ref previousBase, x).AsUInt32();
-
+                    Vector256<uint> c = Unsafe.Add(ref currentBase, x).AsUInt32();
-                x++;
+
-                i += 2;
+                    Vector256<uint> eq = Avx2.CompareEqual(p, c);
-                remaining -= 2;
+                    Vector256<uint> r = Avx2.BlendVariable(c, r256, Avx2.And(eq, vmb256));
+
+                    if (nextFrame != null)
+                    {
+                        Vector256<int> n = Avx2.ShiftRightLogical(Unsafe.Add(ref nextBase, x).AsUInt32(), 24).AsInt32();
+                        eq = Avx2.AndNot(Avx2.CompareGreaterThan(Avx2.ShiftRightLogical(c, 24).AsInt32(), n).AsUInt32(), eq);
+                    }
+
+                    Unsafe.Add(ref resultBase, x) = r.AsByte();
+
+                    uint msk = (uint)Avx2.MoveMask(eq.AsByte());
+                    msk = ~msk;
+
+                    if (msk != 0)
+                    {
+                        // If is diff is found, the left side is marked by the min of previously found left side and the start position.
+                        // The right is the max of the previously found right side and the end position.
+                        int start = i + (BitOperations.TrailingZeroCount(msk) / sizeof(uint));
+                        int end = i + (8 - (BitOperations.LeadingZeroCount(msk) / sizeof(uint)));
+                        left = Math.Min(left, start);
+                        right = Math.Max(right, end);
+                        hasRowDiff = true;
+                        hasDiff = true;
+                    }
+
+                    x++;
+                    i += 8;
+                    remaining -= 8;
+                }
             }
 
             for (i = remaining; i > 0; i--)
             {
                 x = (uint)(length - i);
 
-                Vector4 p = Unsafe.Add(ref Unsafe.As<Vector256<float>, Vector4>(ref previousBase), x);
+                Rgba32 p = Unsafe.Add(ref MemoryMarshal.GetReference(previous), x);
-                Vector4 c = Unsafe.Add(ref Unsafe.As<Vector256<float>, Vector4>(ref currentBase), x);
+                Rgba32 c = Unsafe.Add(ref MemoryMarshal.GetReference(current), x);
-                ref Vector4 r = ref Unsafe.Add(ref Unsafe.As<Vector256<float>, Vector4>(ref resultBase), x);
+                Rgba32 n = Unsafe.Add(ref MemoryMarshal.GetReference(next), x);
+                ref Rgba32 r = ref Unsafe.Add(ref MemoryMarshal.GetReference(result), x);
 
-                if (p != c)
+                bool peq = c.Rgba == (previousFrame != null ? p.Rgba : bg.Rgba);
-                {
+                Rgba32 val = (blend & peq) ? replacement : c;
-                    r = c;
+
+                peq &= nextFrame == null || (n.Rgba >> 24 >= c.Rgba >> 24);
+                r = val;
 
+                if (!peq)
+                {
                     // If is diff is found, the left side is marked by the min of previously found left side and the diff position.
                     // The right is the max of the previously found right side and the diff position + 1.
                     left = Math.Min(left, (int)x);
@@ -127,10 +152,6 @@ internal static class AnimationUtilities
                     hasRowDiff = true;
                     hasDiff = true;
                 }
-                else
-                {
-                    r = replacement;
-                }
             }
 
             if (hasRowDiff)
@@ -143,7 +164,7 @@ internal static class AnimationUtilities
                 bottom = y + 1;
             }
 
-            PixelOperations<TPixel>.Instance.FromVector4Destructive(configuration, result, resultFrame.DangerousGetPixelRowMemory(y).Span, PixelConversionModifiers.Scale);
+            PixelOperations<TPixel>.Instance.FromRgba32(configuration, result, resultFrame.DangerousGetPixelRowMemory(y).Span);
         }
 
         Rectangle bounds = Rectangle.FromLTRB(
@@ -163,19 +184,6 @@ internal static class AnimationUtilities
 
         return (hasDiff, bounds);
     }
-
-    public static void CopySource<TPixel>(ImageFrame<TPixel> source, ImageFrame<TPixel> destination, Rectangle bounds)
-        where TPixel : unmanaged, IPixel<TPixel>
-    {
-        Buffer2DRegion<TPixel> sourceBuffer = source.PixelBuffer.GetRegion(bounds);
-        Buffer2DRegion<TPixel> destBuffer = destination.PixelBuffer.GetRegion(bounds);
-        for (int y = 0; y < destBuffer.Height; y++)
-        {
-            Span<TPixel> sourceRow = sourceBuffer.DangerousGetRowSpan(y);
-            Span<TPixel> destRow = destBuffer.DangerousGetRowSpan(y);
-            sourceRow.CopyTo(destRow);
-        }
-    }
 }
 
 #pragma warning disable SA1201 // Elements should appear in the correct order

src/ImageSharp/Formats/Gif/GifEncoderCore.cs

@@ -264,10 +264,13 @@ internal sealed class GifEncoderCore : IImageEncoderInternals
                 hasPaletteQuantizer = true;
             }
 
+            ImageFrame<TPixel>? nextFrame = i < image.Frames.Count - 1 ? image.Frames[i + 1] : null;
+
             this.EncodeAdditionalFrame(
                 stream,
                 previousFrame,
                 currentFrame,
+                nextFrame,
                 encodingFrame,
                 useLocal,
                 gifMetadata,
@@ -311,6 +314,7 @@ internal sealed class GifEncoderCore : IImageEncoderInternals
         Stream stream,
         ImageFrame<TPixel> previousFrame,
         ImageFrame<TPixel> currentFrame,
+        ImageFrame<TPixel>? nextFrame,
         ImageFrame<TPixel> encodingFrame,
         bool useLocal,
         GifFrameMetadata metadata,
@@ -325,7 +329,15 @@ internal sealed class GifEncoderCore : IImageEncoderInternals
         ImageFrame<TPixel>? previous = previousDisposal == GifDisposalMethod.RestoreToBackground ? null : previousFrame;
 
         // Deduplicate and quantize the frame capturing only required parts.
-        (bool difference, Rectangle bounds) = AnimationUtilities.DeDuplicatePixels(this.configuration, previous, currentFrame, encodingFrame, Vector4.Zero);
+        (bool difference, Rectangle bounds) =
+            AnimationUtilities.DeDuplicatePixels(
+                this.configuration,
+                previous,
+                currentFrame,
+                nextFrame,
+                encodingFrame,
+                Color.Transparent,
+                true);
 
         using IndexedImageFrame<TPixel> quantized = this.QuantizeAdditionalFrameAndUpdateMetadata(
                 encodingFrame,

src/ImageSharp/Formats/Png/PngEncoderCore.cs

@@ -3,7 +3,6 @@
 
 using System.Buffers;
 using System.Buffers.Binary;
-using System.Numerics;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using SixLabors.ImageSharp.Common.Helpers;
@@ -208,21 +207,22 @@ internal sealed class PngEncoderCore : IImageEncoderInternals, IDisposable
 
             for (int i = 1; i < image.Frames.Count; i++)
             {
-                currentFrame = image.Frames[i];
-                frameMetadata = GetPngFrameMetadata(currentFrame);
-
                 ImageFrame<TPixel>? prev = previousDisposal == PngDisposalMethod.RestoreToBackground ? null : previousFrame;
-                (bool difference, Rectangle bounds) = AnimationUtilities.DeDuplicatePixels(image.Configuration, prev, currentFrame, encodingFrame, Vector4.Zero);
+                currentFrame = image.Frames[i];
+                ImageFrame<TPixel>? nextFrame = i < image.Frames.Count - 1 ? image.Frames[i + 1] : null;
 
-                if (difference && previousDisposal != PngDisposalMethod.RestoreToBackground)
+                frameMetadata = GetPngFrameMetadata(currentFrame);
-                {
+                bool blend = frameMetadata.BlendMethod == PngBlendMethod.Over;
-                    if (frameMetadata.BlendMethod == PngBlendMethod.Source)
+
-                    {
+                (bool difference, Rectangle bounds) =
-                        // We've potentially introduced transparency within our area of interest
+                    AnimationUtilities.DeDuplicatePixels(
-                        // so we need to overwrite the changed area with the full data.
+                        image.Configuration,
-                        AnimationUtilities.CopySource(currentFrame, encodingFrame, bounds);
+                        prev,
-                    }
+                        currentFrame,
-                }
+                        nextFrame,
+                        encodingFrame,
+                        Color.Transparent,
+                        blend);
 
                 if (clearTransparency)
                 {

src/ImageSharp/Formats/Webp/WebpEncoderCore.cs

@@ -1,7 +1,6 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
-using System.Numerics;
 using SixLabors.ImageSharp.Formats.Webp.Lossless;
 using SixLabors.ImageSharp.Formats.Webp.Lossy;
 using SixLabors.ImageSharp.Memory;
@@ -161,22 +160,23 @@ internal sealed class WebpEncoderCore : IImageEncoderInternals
 
                 for (int i = 1; i < image.Frames.Count; i++)
                 {
-                    ImageFrame<TPixel> currentFrame = image.Frames[i];
-                    frameMetadata = WebpCommonUtils.GetWebpFrameMetadata(currentFrame);
-
                     ImageFrame<TPixel>? prev = previousDisposal == WebpDisposalMethod.RestoreToBackground ? null : previousFrame;
+                    ImageFrame<TPixel> currentFrame = image.Frames[i];
+                    ImageFrame<TPixel>? nextFrame = i < image.Frames.Count - 1 ? image.Frames[i + 1] : null;
 
-                    (bool difference, Rectangle bounds) = AnimationUtilities.DeDuplicatePixels(image.Configuration, prev, currentFrame, encodingFrame, Vector4.Zero, ClampingMode.Even);
+                    frameMetadata = WebpCommonUtils.GetWebpFrameMetadata(currentFrame);
-
+                    bool blend = frameMetadata.BlendMethod == WebpBlendMethod.Over;
-                    if (difference && previousDisposal != WebpDisposalMethod.RestoreToBackground)
+
-                    {
+                    (bool difference, Rectangle bounds) =
-                        if (frameMetadata.BlendMethod == WebpBlendMethod.Source)
+                        AnimationUtilities.DeDuplicatePixels(
-                        {
+                            image.Configuration,
-                            // We've potentially introduced transparency within our area of interest
+                            prev,
-                            // so we need to overwrite the changed area with the full data.
+                            currentFrame,
-                            AnimationUtilities.CopySource(currentFrame, encodingFrame, bounds);
+                            nextFrame,
-                        }
+                            encodingFrame,
-                    }
+                            Color.Transparent,
+                            blend,
+                            ClampingMode.Even);
 
                     using Vp8LEncoder animatedEncoder = new(
                         this.memoryAllocator,
@@ -232,21 +232,23 @@ internal sealed class WebpEncoderCore : IImageEncoderInternals
 
                 for (int i = 1; i < image.Frames.Count; i++)
                 {
+                    ImageFrame<TPixel>? prev = previousDisposal == WebpDisposalMethod.RestoreToBackground ? null : previousFrame;
                     ImageFrame<TPixel> currentFrame = image.Frames[i];
-                    frameMetadata = WebpCommonUtils.GetWebpFrameMetadata(currentFrame);
+                    ImageFrame<TPixel>? nextFrame = i < image.Frames.Count - 1 ? image.Frames[i + 1] : null;
 
-                    ImageFrame<TPixel>? prev = previousDisposal == WebpDisposalMethod.RestoreToBackground ? null : previousFrame;
+                    frameMetadata = WebpCommonUtils.GetWebpFrameMetadata(currentFrame);
-                    (bool difference, Rectangle bounds) = AnimationUtilities.DeDuplicatePixels(image.Configuration, prev, currentFrame, encodingFrame, Vector4.Zero, ClampingMode.Even);
+                    bool blend = frameMetadata.BlendMethod == WebpBlendMethod.Over;
-
+
-                    if (difference && previousDisposal != WebpDisposalMethod.RestoreToBackground)
+                    (bool difference, Rectangle bounds) =
-                    {
+                        AnimationUtilities.DeDuplicatePixels(
-                        if (frameMetadata.BlendMethod == WebpBlendMethod.Source)
+                            image.Configuration,
-                        {
+                            prev,
-                            // We've potentially introduced transparency within our area of interest
+                            currentFrame,
-                            // so we need to overwrite the changed area with the full data.
+                            nextFrame,
-                            AnimationUtilities.CopySource(currentFrame, encodingFrame, bounds);
+                            encodingFrame,
-                        }
+                            Color.Transparent,
-                    }
+                            blend,
+                            ClampingMode.Even);
 
                     using Vp8Encoder animatedEncoder = new(
                         this.memoryAllocator,

tests/ImageSharp.Tests/TestImages.cs

@@ -480,6 +480,7 @@ public static class TestImages
         public const string LargeComment = "Gif/large_comment.gif";
         public const string GlobalQuantizationTest = "Gif/GlobalQuantizationTest.gif";
         public const string MixedDisposal = "Gif/mixed-disposal.gif";
+        public const string M4nb = "Gif/m4nb.gif";
 
         // Test images from https://github.com/robert-ancell/pygif/tree/master/test-suite
         public const string ZeroSize = "Gif/image-zero-size.gif";
@@ -511,6 +512,7 @@ public static class TestImages
 
         public static readonly string[] Animated =
         {
+            M4nb,
             Giphy,
             Cheers,
             Kumin,

tests/Images/Input/Gif/m4nb.gif

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:b5b495caf1eb1f1cf7b15a1998faa33a6f4a49999e5edd435d4ff91265ff1ce5
+size 2100