Parallel.For() in ProcessBlockColorsIntoJpegImageChannels

src/ImageSharp.Formats.Jpeg/JpegDecoderCore.cs

@@ -468,12 +468,15 @@ namespace ImageSharp.Formats
         /// <typeparam name="TColor">The pixel type</typeparam>
         private void ProcessBlockColorsIntoJpegImageChannels<TColor>()
             where TColor : struct, IPackedPixel, IEquatable<TColor>
+        {
+            Parallel.For(
+                0,
+                this.ComponentCount,
+                componentIndex =>
                     {
                         JpegScanDecoder scanDecoder = default(JpegScanDecoder);
                         JpegScanDecoder.Init(&scanDecoder);
 
-            for (int componentIndex = 0; componentIndex < this.ComponentCount; componentIndex++)
-            {
                         scanDecoder.ComponentIndex = componentIndex;
                         DecodedBlockMemento[] blockArray = this.DecodedBlocks[componentIndex];
                         for (int i = 0; i < blockArray.Length; i++)
@@ -481,7 +484,7 @@ namespace ImageSharp.Formats
                             scanDecoder.LoadMemento(ref blockArray[i]);
                             scanDecoder.ProcessBlockColors(this);
                         }
-            }
+                    });
         }
 
         /// <summary>

tests/ImageSharp.Tests/Formats/Jpg/JpegProfilingBenchmarks.cs

@@ -32,7 +32,7 @@ namespace ImageSharp.Tests
             TestImages.Jpeg.Baseline.Jpeg444,
         };
 
-        // [Theory] // Benchmark, enable manually
+        [Theory] // Benchmark, enable manually
         [MemberData(nameof(DecodeJpegData))]
         public void DecodeJpeg(string fileName)
         {