Removed redundant color converters creation, updated benchmarks

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverterAvx.cs

@@ -25,8 +25,13 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components
             {
             }
 
+            /// <summary>
+            /// Gets a value indicating whether this converter is supported on current hardware.
+            /// </summary>
+            public static bool IsSupported => Avx.IsSupported;
+
             /// <inheritdoc/>
-            public override bool IsAvailable => Avx.IsSupported;
+            public override bool IsAvailable => IsSupported;
         }
     }
 }

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverterBase.cs

@@ -93,73 +93,116 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components
         /// </summary>
         private static JpegColorConverterBase[] CreateConverters()
         {
-            var converters = new List<JpegColorConverterBase>();
+            // 5 color types with 2 supported precisions: 8 bit & 12 bit
+            const int colorConvertersCount = 5 * 2;
+
+            var converters = new JpegColorConverterBase[colorConvertersCount];
 
             // 8-bit converters
-            converters.AddRange(GetYCbCrConverters(8));
-            converters.AddRange(GetYccKConverters(8));
-            converters.AddRange(GetCmykConverters(8));
-            converters.AddRange(GetGrayScaleConverters(8));
-            converters.AddRange(GetRgbConverters(8));
+            converters[0] = GetYCbCrConverter(8);
+            converters[1] = GetYccKConverter(8);
+            converters[2] = GetCmykConverter(8);
+            converters[3] = GetGrayScaleConverter(8);
+            converters[4] = GetRgbConverter(8);
 
             // 12-bit converters
-            converters.AddRange(GetYCbCrConverters(12));
-            converters.AddRange(GetYccKConverters(12));
-            converters.AddRange(GetCmykConverters(12));
-            converters.AddRange(GetGrayScaleConverters(12));
-            converters.AddRange(GetRgbConverters(12));
+            converters[5] = GetYCbCrConverter(12);
+            converters[6] = GetYccKConverter(12);
+            converters[7] = GetCmykConverter(12);
+            converters[8] = GetGrayScaleConverter(12);
+            converters[9] = GetRgbConverter(12);
 
-            return converters.Where(x => x.IsAvailable).ToArray();
+            return converters;
         }
 
         /// <summary>
         /// Returns the <see cref="JpegColorConverterBase"/>s for the YCbCr colorspace.
         /// </summary>
-        private static IEnumerable<JpegColorConverterBase> GetYCbCrConverters(int precision)
+        private static JpegColorConverterBase GetYCbCrConverter(int precision)
         {
-            yield return new YCbCrAvx(precision);
-            yield return new YCbCrVector(precision);
-            yield return new YCbCrScalar(precision);
+            if (JpegColorConverterAvx.IsSupported)
+            {
+                return new YCbCrAvx(precision);
+            }
+
+            if (JpegColorConverterVector.IsSupported)
+            {
+                return new YCbCrVector(precision);
+            }
+
+            return new YCbCrScalar(precision);
         }
 
         /// <summary>
         /// Returns the <see cref="JpegColorConverterBase"/>s for the YccK colorspace.
         /// </summary>
-        private static IEnumerable<JpegColorConverterBase> GetYccKConverters(int precision)
+        private static JpegColorConverterBase GetYccKConverter(int precision)
         {
-            yield return new YccKAvx(precision);
-            yield return new YccKVector(precision);
-            yield return new YccKScalar(precision);
+            if (JpegColorConverterAvx.IsSupported)
+            {
+                return new YccKAvx(precision);
+            }
+
+            if (JpegColorConverterVector.IsSupported)
+            {
+                return new YccKVector(precision);
+            }
+
+            return new YccKScalar(precision);
         }
 
         /// <summary>
         /// Returns the <see cref="JpegColorConverterBase"/>s for the CMYK colorspace.
         /// </summary>
-        private static IEnumerable<JpegColorConverterBase> GetCmykConverters(int precision)
+        private static JpegColorConverterBase GetCmykConverter(int precision)
         {
-            yield return new CmykAvx(precision);
-            yield return new CmykVector(precision);
-            yield return new CmykScalar(precision);
+            if (JpegColorConverterAvx.IsSupported)
+            {
+                return new CmykAvx(precision);
+            }
+
+            if (JpegColorConverterVector.IsSupported)
+            {
+                return new CmykVector(precision);
+            }
+
+            return new CmykScalar(precision);
         }
 
         /// <summary>
         /// Returns the <see cref="JpegColorConverterBase"/>s for the gray scale colorspace.
         /// </summary>
-        private static IEnumerable<JpegColorConverterBase> GetGrayScaleConverters(int precision)
+        private static JpegColorConverterBase GetGrayScaleConverter(int precision)
         {
-            yield return new GrayscaleAvx(precision);
-            yield return new GrayScaleVector(precision);
-            yield return new GrayscaleScalar(precision);
+            if (JpegColorConverterAvx.IsSupported)
+            {
+                return new GrayscaleAvx(precision);
+            }
+
+            if (JpegColorConverterVector.IsSupported)
+            {
+                return new GrayScaleVector(precision);
+            }
+
+            return new GrayscaleScalar(precision);
         }
 
         /// <summary>
         /// Returns the <see cref="JpegColorConverterBase"/>s for the RGB colorspace.
         /// </summary>
-        private static IEnumerable<JpegColorConverterBase> GetRgbConverters(int precision)
+        private static JpegColorConverterBase GetRgbConverter(int precision)
         {
-            yield return new RgbAvx(precision);
-            yield return new RgbVector(precision);
-            yield return new RgbScalar(precision);
+            if (JpegColorConverterAvx.IsSupported)
+            {
+                return new RgbAvx(precision);
+            }
+
+            if (JpegColorConverterVector.IsSupported)
+            {
+                return new RgbScalar(precision);
+            }
+
+            return new GrayscaleScalar(precision);
         }
 
         /// <summary>

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverterVector.cs

@@ -26,8 +26,13 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components
             {
             }
 
+            /// <summary>
+            /// Gets a value indicating whether this converter is supported on current hardware.
+            /// </summary>
+            public static bool IsSupported => Vector.IsHardwareAccelerated && Vector<float>.Count % 4 == 0;
+
             /// <inheritdoc/>
-            public sealed override bool IsAvailable => Vector.IsHardwareAccelerated && Vector<float>.Count % 4 == 0;
+            public sealed override bool IsAvailable => IsSupported;
 
             /// <inheritdoc/>
             public sealed override void ConvertToRgbInplace(in ComponentValues values)

src/ImageSharp/Formats/Jpeg/Components/Encoder/HuffmanScanEncoder.cs

@@ -149,7 +149,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder
             {
                 case JpegEncodingColor.YCbCrRatio444:
                 case JpegEncodingColor.Rgb:
-                    this.EncodeThreeComponentScanBaselineInterleaved444(frame, converter, cancellationToken);
+                    this.EncodeThreeComponentBaselineInterleavedScanNoSubsampling(frame, converter, cancellationToken);
                     break;
                 default:
                     this.EncodeScanBaselineInterleaved(frame, converter, cancellationToken);
@@ -310,12 +310,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder
         }
 
         /// <summary>
-        /// Encodes scan in baseline interleaved mode with exactly 3 components with 4:4:4 sampling.
+        /// Encodes scan in baseline interleaved mode with exactly 3 components with no subsampling.
         /// </summary>
         /// <param name="frame">Frame to encode.</param>
         /// <param name="converter">Converter from color to spectral.</param>
         /// <param name="cancellationToken">The token to request cancellation.</param>
-        private void EncodeThreeComponentScanBaselineInterleaved444<TPixel>(JpegFrame frame, SpectralConverter<TPixel> converter, CancellationToken cancellationToken)
+        private void EncodeThreeComponentBaselineInterleavedScanNoSubsampling<TPixel>(JpegFrame frame, SpectralConverter<TPixel> converter, CancellationToken cancellationToken)
             where TPixel : unmanaged, IPixel<TPixel>
         {
             nint mcusPerColumn = frame.McusPerColumn;

tests/ImageSharp.Benchmarks/Codecs/Jpeg/EncodeJpegFeatures.cs

@@ -84,16 +84,16 @@ Intel Core i7-6700K CPU 4.00GHz (Skylake), 1 CPU, 8 logical and 4 physical cores
 
 |    Method | TargetColorSpace | Quality |      Mean |     Error |    StdDev |
 |---------- |----------------- |-------- |----------:|----------:|----------:|
-| Benchmark |        Luminance |      75 |  4.575 ms | 0.0233 ms | 0.0207 ms |
-| Benchmark |              Rgb |      75 | 12.477 ms | 0.1051 ms | 0.0932 ms |
-| Benchmark |    YCbCrRatio420 |      75 |  6.421 ms | 0.0464 ms | 0.0434 ms |
-| Benchmark |    YCbCrRatio444 |      75 |  8.449 ms | 0.1246 ms | 0.1166 ms |
-| Benchmark |        Luminance |      90 |  4.863 ms | 0.0120 ms | 0.0106 ms |
-| Benchmark |              Rgb |      90 | 13.287 ms | 0.0548 ms | 0.0513 ms |
-| Benchmark |    YCbCrRatio420 |      90 |  7.012 ms | 0.0533 ms | 0.0499 ms |
-| Benchmark |    YCbCrRatio444 |      90 |  8.916 ms | 0.1285 ms | 0.1202 ms |
-| Benchmark |        Luminance |     100 |  6.665 ms | 0.0136 ms | 0.0113 ms |
-| Benchmark |              Rgb |     100 | 19.734 ms | 0.0477 ms | 0.0446 ms |
-| Benchmark |    YCbCrRatio420 |     100 | 10.541 ms | 0.0925 ms | 0.0865 ms |
-| Benchmark |    YCbCrRatio444 |     100 | 15.587 ms | 0.1695 ms | 0.1586 ms |
+| Benchmark |        Luminance |      75 |  4.618 ms | 0.0263 ms | 0.0233 ms |
+| Benchmark |              Rgb |      75 | 12.543 ms | 0.0650 ms | 0.0608 ms |
+| Benchmark |    YCbCrRatio420 |      75 |  6.639 ms | 0.0778 ms | 0.1256 ms |
+| Benchmark |    YCbCrRatio444 |      75 |  8.590 ms | 0.0570 ms | 0.0505 ms |
+| Benchmark |        Luminance |      90 |  4.902 ms | 0.0307 ms | 0.0288 ms |
+| Benchmark |              Rgb |      90 | 13.447 ms | 0.0468 ms | 0.0415 ms |
+| Benchmark |    YCbCrRatio420 |      90 |  7.218 ms | 0.0586 ms | 0.0548 ms |
+| Benchmark |    YCbCrRatio444 |      90 |  9.150 ms | 0.0779 ms | 0.0729 ms |
+| Benchmark |        Luminance |     100 |  6.731 ms | 0.0325 ms | 0.0304 ms |
+| Benchmark |              Rgb |     100 | 19.831 ms | 0.1009 ms | 0.0788 ms |
+| Benchmark |    YCbCrRatio420 |     100 | 10.541 ms | 0.0423 ms | 0.0396 ms |
+| Benchmark |    YCbCrRatio444 |     100 | 15.345 ms | 0.3276 ms | 0.3065 ms |
 */