Fix issue with encoding 1 by 1 pixel lossless image

src/ImageSharp/Advanced/AotCompilerTools.cs

@@ -7,13 +7,13 @@ using System.Numerics;
 using System.Runtime.CompilerServices;
 using SixLabors.ImageSharp.Formats;
 using SixLabors.ImageSharp.Formats.Bmp;
-using SixLabors.ImageSharp.Formats.Webp;
 using SixLabors.ImageSharp.Formats.Gif;
 using SixLabors.ImageSharp.Formats.Jpeg;
 using SixLabors.ImageSharp.Formats.Jpeg.Components;
 using SixLabors.ImageSharp.Formats.Png;
 using SixLabors.ImageSharp.Formats.Tga;
 using SixLabors.ImageSharp.Formats.Tiff;
+using SixLabors.ImageSharp.Formats.Webp;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing;

src/ImageSharp/Formats/WebP/Lossless/BackwardReferenceEncoder.cs

@@ -81,7 +81,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
 
                 // Keep the best backward references.
                 var histo = new Vp8LHistogram(worst, cacheBitsTmp);
-                var bitCost = histo.EstimateBits();
+                double bitCost = histo.EstimateBits();
 
                 if (lz77TypeBest == 0 || bitCost < bitCostBest)
                 {

src/ImageSharp/Formats/WebP/Lossless/Vp8LEncoder.cs

@@ -65,7 +65,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
         /// <param name="method">Quality/speed trade-off (0=fast, 6=slower-better).</param>
         public Vp8LEncoder(MemoryAllocator memoryAllocator, int width, int height, int quality, int method)
         {
-            var pixelCount = width * height;
+            int pixelCount = width * height;
             int initialSize = pixelCount * 2;
 
             this.quality = Numerics.Clamp(quality, 0, 100);
@@ -254,7 +254,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
                                                  (crunchConfig.EntropyIdx == EntropyIx.SpatialSubGreen);
                 this.UsePredictorTransform = (crunchConfig.EntropyIdx == EntropyIx.Spatial) ||
                                              (crunchConfig.EntropyIdx == EntropyIx.SpatialSubGreen);
-                this.UseCrossColorTransform = redAndBlueAlwaysZero ? false : this.UsePredictorTransform;
+                this.UseCrossColorTransform = !redAndBlueAlwaysZero && this.UsePredictorTransform;
                 this.AllocateTransformBuffer(width, height);
 
                 // Reset any parameter in the encoder that is set in the previous iteration.
@@ -335,14 +335,14 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
             int height = image.Height;
 
             // Check if we only deal with a small number of colors and should use a palette.
-            var usePalette = this.AnalyzeAndCreatePalette(image);
+            bool usePalette = this.AnalyzeAndCreatePalette(image);
 
             // Empirical bit sizes.
             this.HistoBits = GetHistoBits(this.method, usePalette, width, height);
             this.TransformBits = GetTransformBits(this.method, this.HistoBits);
 
             // Try out multiple LZ77 on images with few colors.
-            var nlz77s = (this.PaletteSize > 0 && this.PaletteSize <= 16) ? 2 : 1;
+            int nlz77s = (this.PaletteSize > 0 && this.PaletteSize <= 16) ? 2 : 1;
             EntropyIx entropyIdx = this.AnalyzeEntropy(image, usePalette, this.PaletteSize, this.TransformBits, out redAndBlueAlwaysZero);
 
             bool doNotCache = false;
@@ -382,7 +382,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
             // Fill in the different LZ77s.
             foreach (CrunchConfig crunchConfig in crunchConfigs)
             {
-                for (var j = 0; j < nlz77s; ++j)
+                for (int j = 0; j < nlz77s; ++j)
                 {
                     crunchConfig.SubConfigs.Add(new CrunchSubConfig
                     {
@@ -398,7 +398,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
         private void EncodeImage(Span<uint> bgra, Vp8LHashChain hashChain, Vp8LBackwardRefs[] refsArray, int width, int height, bool useCache, CrunchConfig config, int cacheBits, int histogramBits)
         {
             int histogramImageXySize = LosslessUtils.SubSampleSize(width, histogramBits) * LosslessUtils.SubSampleSize(height, histogramBits);
-            var histogramSymbols = new ushort[histogramImageXySize];
+            ushort[] histogramSymbols = new ushort[histogramImageXySize];
             var huffTree = new HuffmanTree[3 * WebpConstants.CodeLengthCodes];
             for (int i = 0; i < huffTree.Length; i++)
             {
@@ -452,8 +452,8 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
                 HistogramEncoder.GetHistoImageSymbols(width, height, refsBest, this.quality, histogramBits, cacheBits, histogramImage, tmpHisto, histogramSymbols);
 
                 // Create Huffman bit lengths and codes for each histogram image.
-                var histogramImageSize = histogramImage.Count;
+                int histogramImageSize = histogramImage.Count;
-                var bitArraySize = 5 * histogramImageSize;
+                int bitArraySize = 5 * histogramImageSize;
                 var huffmanCodes = new HuffmanTreeCode[bitArraySize];
                 for (int i = 0; i < huffmanCodes.Length; i++)
                 {
@@ -601,7 +601,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
         private void EncodeImageNoHuffman(Span<uint> bgra, Vp8LHashChain hashChain, Vp8LBackwardRefs refsTmp1, Vp8LBackwardRefs refsTmp2, int width, int height, int quality)
         {
             int cacheBits = 0;
-            var histogramSymbols = new ushort[1]; // Only one tree, one symbol.
+            ushort[] histogramSymbols = new ushort[1]; // Only one tree, one symbol.
 
             var huffmanCodes = new HuffmanTreeCode[5];
             for (int i = 0; i < huffmanCodes.Length; i++)
@@ -728,8 +728,8 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
         private void StoreFullHuffmanCode(HuffmanTree[] huffTree, HuffmanTreeToken[] tokens, HuffmanTreeCode tree)
         {
             int i;
-            var codeLengthBitDepth = new byte[WebpConstants.CodeLengthCodes];
+            byte[] codeLengthBitDepth = new byte[WebpConstants.CodeLengthCodes];
-            var codeLengthBitDepthSymbols = new short[WebpConstants.CodeLengthCodes];
+            short[] codeLengthBitDepthSymbols = new short[WebpConstants.CodeLengthCodes];
             var huffmanCode = new HuffmanTreeCode
             {
                 NumSymbols = WebpConstants.CodeLengthCodes,
@@ -738,9 +738,9 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
             };
 
             this.bitWriter.PutBits(0, 1);
-            var numTokens = HuffmanUtils.CreateCompressedHuffmanTree(tree, tokens);
+            int numTokens = HuffmanUtils.CreateCompressedHuffmanTree(tree, tokens);
-            var histogram = new uint[WebpConstants.CodeLengthCodes + 1];
+            uint[] histogram = new uint[WebpConstants.CodeLengthCodes + 1];
-            var bufRle = new bool[WebpConstants.CodeLengthCodes + 1];
+            bool[] bufRle = new bool[WebpConstants.CodeLengthCodes + 1];
             for (i = 0; i < numTokens; i++)
             {
                 histogram[tokens[i].Code]++;
@@ -758,7 +758,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
                 int ix = tokens[i].Code;
                 if (ix == 0 || ix == 17 || ix == 18)
                 {
-                    trimmedLength--;   // discount trailing zeros.
+                    trimmedLength--;   // Discount trailing zeros.
                     trailingZeroBits += codeLengthBitDepth[ix];
                     if (ix == 17)
                     {
@@ -775,8 +775,8 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
                 }
             }
 
-            var writeTrimmedLength = trimmedLength > 1 && trailingZeroBits > 12;
+            bool writeTrimmedLength = trimmedLength > 1 && trailingZeroBits > 12;
-            var length = writeTrimmedLength ? trimmedLength : numTokens;
+            int length = writeTrimmedLength ? trimmedLength : numTokens;
             this.bitWriter.PutBits((uint)(writeTrimmedLength ? 1 : 0), 1);
             if (writeTrimmedLength)
             {
@@ -976,8 +976,8 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
                 prevRow = currentRow;
             }
 
-            var entropyComp = new double[(int)HistoIx.HistoTotal];
+            double[] entropyComp = new double[(int)HistoIx.HistoTotal];
-            var entropy = new double[(int)EntropyIx.NumEntropyIx];
+            double[] entropy = new double[(int)EntropyIx.NumEntropyIx];
             int lastModeToAnalyze = usePalette ? (int)EntropyIx.Palette : (int)EntropyIx.SpatialSubGreen;
 
             // Let's add one zero to the predicted histograms. The zeros are removed
@@ -1195,7 +1195,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
             }
             else
             {
-                var buffer = new uint[PaletteInvSize];
+                uint[] buffer = new uint[PaletteInvSize];
 
                 // Try to find a perfect hash function able to go from a color to an index
                 // within 1 << PaletteInvSize in order to build a hash map to go from color to index in palette.
@@ -1246,8 +1246,8 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
                 }
                 else
                 {
-                    var idxMap = new uint[paletteSize];
+                    uint[] idxMap = new uint[paletteSize];
-                    var paletteSorted = new uint[paletteSize];
+                    uint[] paletteSorted = new uint[paletteSize];
                     PrepareMapToPalette(palette, paletteSize, paletteSorted, idxMap);
                     ApplyPaletteForWithIdxMap(width, height, palette, src, srcStride, dst, dstStride, tmpRow, idxMap, xBits, paletteSorted, paletteSize);
                 }
@@ -1464,7 +1464,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
                 }
             }
 
-            var end = 5 * histogramImage.Count;
+            int end = 5 * histogramImage.Count;
             for (int i = 0; i < end; i++)
             {
                 int bitLength = huffmanCodes[i].NumSymbols;
@@ -1477,7 +1477,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
             }
 
             // Create Huffman trees.
-            var bufRle = new bool[maxNumSymbols];
+            bool[] bufRle = new bool[maxNumSymbols];
             var huffTree = new HuffmanTree[3 * maxNumSymbols];
             for (int i = 0; i < huffTree.Length; i++)
             {

src/ImageSharp/Formats/WebP/Lossless/Vp8LHashChain.cs

@@ -60,16 +60,23 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
             int iterMax = GetMaxItersForQuality(quality);
             int windowSize = GetWindowSizeForHashChain(quality, xSize);
             int pos;
+
+            if (size <= 2)
+            {
+                this.OffsetLength[0] = 0;
+                return;
+            }
+
             using IMemoryOwner<int> hashToFirstIndexBuffer = memoryAllocator.Allocate<int>(HashSize);
             Span<int> hashToFirstIndex = hashToFirstIndexBuffer.GetSpan();
 
             // Initialize hashToFirstIndex array to -1.
             hashToFirstIndex.Fill(-1);
 
-            var chain = new int[size];
+            int[] chain = new int[size];
 
             // Fill the chain linking pixels with the same hash.
-            var bgraComp = bgra[0] == bgra[1];
+            bool bgraComp = bgra.Length > 1 && bgra[0] == bgra[1];
             for (pos = 0; pos < size - 2;)
             {
                 uint hashCode;
@@ -78,7 +85,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
                 {
                     // Consecutive pixels with the same color will share the same hash.
                     // We therefore use a different hash: the color and its repetition length.
-                    var tmp = new uint[2];
+                    uint[] tmp = new uint[2];
                     uint len = 1;
                     tmp[0] = bgra[pos];
 
@@ -168,7 +175,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
                     pos = minPos - 1;
                 }
 
-                var bestBgra = bgra.Slice(bgraStart)[bestLength];
+                uint bestBgra = bgra.Slice(bgraStart)[bestLength];
 
                 for (; pos >= minPos && (--iter > 0); pos = chain[pos])
                 {
@@ -194,7 +201,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
 
                 // We have the best match but in case the two intervals continue matching
                 // to the left, we have the best matches for the left-extended pixels.
-                var maxBasePosition = (uint)basePosition;
+                uint maxBasePosition = (uint)basePosition;
                 while (true)
                 {
                     this.OffsetLength[basePosition] = (bestDistance << BackwardReferenceEncoder.MaxLengthBits) | (uint)bestLength;
@@ -231,16 +238,10 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
         }
 
         [MethodImpl(InliningOptions.ShortMethod)]
-        public int FindLength(int basePosition)
+        public int FindLength(int basePosition) => (int)(this.OffsetLength[basePosition] & ((1U << BackwardReferenceEncoder.MaxLengthBits) - 1));
-        {
-            return (int)(this.OffsetLength[basePosition] & ((1U << BackwardReferenceEncoder.MaxLengthBits) - 1));
-        }
 
         [MethodImpl(InliningOptions.ShortMethod)]
-        public int FindOffset(int basePosition)
+        public int FindOffset(int basePosition) => (int)(this.OffsetLength[basePosition] >> BackwardReferenceEncoder.MaxLengthBits);
-        {
-            return (int)(this.OffsetLength[basePosition] >> BackwardReferenceEncoder.MaxLengthBits);
-        }
 
         /// <summary>
         /// Calculates the hash for a pixel pair.
@@ -252,7 +253,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
         {
             uint key = bgra[1] * HashMultiplierHi;
             key += bgra[0] * HashMultiplierLo;
-            key = key >> (32 - HashBits);
+            key >>= 32 - HashBits;
             return key;
         }
 
@@ -263,10 +264,7 @@ namespace SixLabors.ImageSharp.Formats.Webp.Lossless
         /// <param name="quality">The quality.</param>
         /// <returns>Number of hash chain lookups.</returns>
         [MethodImpl(InliningOptions.ShortMethod)]
-        private static int GetMaxItersForQuality(int quality)
+        private static int GetMaxItersForQuality(int quality) => 8 + (quality * quality / 128);
-        {
-            return 8 + (quality * quality / 128);
-        }
 
         [MethodImpl(InliningOptions.ShortMethod)]
         private static int GetWindowSizeForHashChain(int quality, int xSize)

src/ImageSharp/Formats/WebP/WebpEncoderCore.cs

@@ -3,7 +3,6 @@
 
 using System.IO;
 using System.Threading;
-using System.Threading.Tasks;
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Formats.Webp.Lossless;
 using SixLabors.ImageSharp.Formats.Webp.Lossy;

tests/ImageSharp.Benchmarks/Codecs/EncodeTiff.cs

@@ -61,7 +61,7 @@ namespace SixLabors.ImageSharp.Benchmarks.Codecs
             ImageCodecInfo codec = FindCodecForType("image/tiff");
             using var parameters = new EncoderParameters(1)
             {
-                Param = {[0] = new EncoderParameter(Encoder.Compression, (long)Cast(this.Compression))}
+                Param = { [0] = new EncoderParameter(Encoder.Compression, (long)Cast(this.Compression)) }
             };
 
             using var memoryStream = new MemoryStream();
@@ -73,12 +73,6 @@ namespace SixLabors.ImageSharp.Benchmarks.Codecs
         {
             TiffPhotometricInterpretation photometricInterpretation = TiffPhotometricInterpretation.Rgb;
 
-            // Workaround for 1-bit bug
-            if (this.Compression == TiffCompression.CcittGroup3Fax || this.Compression == TiffCompression.Ccitt1D)
-            {
-                photometricInterpretation = TiffPhotometricInterpretation.WhiteIsZero;
-            }
-
             var encoder = new TiffEncoder() { Compression = this.Compression, PhotometricInterpretation = photometricInterpretation };
             using var memoryStream = new MemoryStream();
             this.core.SaveAsTiff(memoryStream, encoder);

tests/ImageSharp.Tests/Formats/WebP/WebpEncoderTests.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
+using System.IO;
 using SixLabors.ImageSharp.Formats.Webp;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison;
@@ -26,7 +27,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Webp
             };
 
             using Image<TPixel> image = provider.GetImage();
-            var testOutputDetails = string.Concat("lossless", "_q", quality);
+            string testOutputDetails = string.Concat("lossless", "_q", quality);
             image.VerifyEncoder(provider, "webp", testOutputDetails, encoder);
         }
 
@@ -49,7 +50,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Webp
             };
 
             using Image<TPixel> image = provider.GetImage();
-            var testOutputDetails = string.Concat("lossless", "_m", method);
+            string testOutputDetails = string.Concat("lossless", "_m", method);
             image.VerifyEncoder(provider, "webp", testOutputDetails, encoder);
         }
 
@@ -67,7 +68,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Webp
             };
 
             using Image<TPixel> image = provider.GetImage();
-            var testOutputDetails = string.Concat("lossy", "_q", quality);
+            string testOutputDetails = string.Concat("lossy", "_q", quality);
             image.VerifyEncoder(provider, "webp", testOutputDetails, encoder, customComparer: GetComparer(quality));
         }
 
@@ -91,10 +92,22 @@ namespace SixLabors.ImageSharp.Tests.Formats.Webp
             };
 
             using Image<TPixel> image = provider.GetImage();
-            var testOutputDetails = string.Concat("lossy", "_m", method);
+            string testOutputDetails = string.Concat("lossy", "_m", method);
             image.VerifyEncoder(provider, "webp", testOutputDetails, encoder, customComparer: GetComparer(quality));
         }
 
+        [Fact]
+        public void Encode_Lossless_OneByOnePixel_Works()
+        {
+            // Just make sure, encoding 1 pixel by 1 pixel does not throw an exception.
+            using var image = new Image<Rgba32>(1, 1);
+            var encoder = new WebpEncoder() { Lossy = false };
+            using (var memStream = new MemoryStream())
+            {
+                image.SaveAsWebp(memStream, encoder);
+            }
+        }
+
         private static ImageComparer GetComparer(int quality)
         {
             float tolerance = 0.01f; // ~1.0%

tests/ImageSharp.Tests/Metadata/ImageMetadataTests.cs

@@ -98,8 +98,8 @@ namespace SixLabors.ImageSharp.Tests.Metadata
 
                 image.Metadata.SyncProfiles();
 
-                Assert.Equal(400, ((Rational)image.Metadata.ExifProfile.GetValue(ExifTag.XResolution).Value).ToDouble());
+                Assert.Equal(400, image.Metadata.ExifProfile.GetValue(ExifTag.XResolution).Value.ToDouble());
-                Assert.Equal(500, ((Rational)image.Metadata.ExifProfile.GetValue(ExifTag.YResolution).Value).ToDouble());
+                Assert.Equal(500, image.Metadata.ExifProfile.GetValue(ExifTag.YResolution).Value.ToDouble());
             }
         }
     }

tests/ImageSharp.Tests/TestUtilities/TestEnvironment.Formats.cs

@@ -5,12 +5,12 @@ using System;
 using System.IO;
 using SixLabors.ImageSharp.Formats;
 using SixLabors.ImageSharp.Formats.Bmp;
-using SixLabors.ImageSharp.Formats.Webp;
 using SixLabors.ImageSharp.Formats.Gif;
 using SixLabors.ImageSharp.Formats.Jpeg;
 using SixLabors.ImageSharp.Formats.Png;
 using SixLabors.ImageSharp.Formats.Tga;
 using SixLabors.ImageSharp.Formats.Tiff;
+using SixLabors.ImageSharp.Formats.Webp;
 using SixLabors.ImageSharp.Tests.TestUtilities.ReferenceCodecs;
 
 namespace SixLabors.ImageSharp.Tests

tests/ImageSharp.Tests/TestUtilities/Tests/TestEnvironmentTests.cs

@@ -5,9 +5,9 @@ using System;
 using System.IO;
 using SixLabors.ImageSharp.Formats;
 using SixLabors.ImageSharp.Formats.Bmp;
-using SixLabors.ImageSharp.Formats.Webp;
 using SixLabors.ImageSharp.Formats.Gif;
 using SixLabors.ImageSharp.Formats.Jpeg;
+using SixLabors.ImageSharp.Formats.Webp;
 using SixLabors.ImageSharp.Tests.TestUtilities.ReferenceCodecs;
 using Xunit;
 using Xunit.Abstractions;