Golang is skipping EXIF reading when it shouldn't.

src/ImageSharp/Formats/Jpeg/PdfJsPort/PdfJsJpegDecoderCore.cs

@@ -22,7 +22,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
 {
     /// <summary>
     /// Performs the jpeg decoding operation.
-    /// Ported from <see href="https://github.com/mozilla/pdf.js/blob/master/src/core/jpg.js"/> with additional fixes to handle common encoding errors
+    /// Originally ported from <see href="https://github.com/mozilla/pdf.js/blob/master/src/core/jpg.js"/>
+    /// with additional fixes for both performance and common encoding errors.
     /// </summary>
     internal sealed class PdfJsJpegDecoderCore : IRawJpegData
     {
@@ -31,7 +32,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
         /// </summary>
         public const int SupportedPrecision = 8;
 
-#pragma warning disable SA1401 // Fields should be private
         /// <summary>
         /// The global configuration
         /// </summary>
@@ -242,7 +242,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
                         case PdfJsJpegConstants.Markers.SOF0:
                         case PdfJsJpegConstants.Markers.SOF1:
                         case PdfJsJpegConstants.Markers.SOF2:
-
                             this.ProcessStartOfFrameMarker(remaining, fileMarker, metadataOnly);
                             break;
 
@@ -291,17 +290,14 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
                             break;
 
                         case PdfJsJpegConstants.Markers.APP0:
-
                             this.ProcessApplicationHeaderMarker(remaining);
                             break;
 
                         case PdfJsJpegConstants.Markers.APP1:
-
                             this.ProcessApp1Marker(remaining);
                             break;
 
                         case PdfJsJpegConstants.Markers.APP2:
-
                             this.ProcessApp2Marker(remaining);
                             break;
 
@@ -320,7 +316,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
                             break;
 
                         case PdfJsJpegConstants.Markers.APP14:
-
                             this.ProcessApp14Marker(remaining);
                             break;
 

tests/ImageSharp.Benchmarks/Codecs/Jpeg/Identify.cs → tests/ImageSharp.Benchmarks/Codecs/Jpeg/IdentifyJpeg.cs

@@ -10,7 +10,7 @@ using SixLabors.ImageSharp.Tests;
 namespace SixLabors.ImageSharp.Benchmarks.Codecs.Jpeg
 {
     [Config(typeof(Config.ShortClr))]
-    public class Identify
+    public class IdentifyJpeg
     {
         private byte[] jpegBytes;
 

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

@@ -478,6 +478,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Jpg
         [InlineData(TestImages.Jpeg.Baseline.Ycck, 32)]
         [InlineData(TestImages.Jpeg.Baseline.Jpeg400, 8)]
         [InlineData(TestImages.Jpeg.Baseline.Snake, 24)]
+        [InlineData(TestImages.Jpeg.Baseline.Jpeg420Exif, 24)]
         public void DetectPixelSizeGolang(string imagePath, int expectedPixelSize)
         {
             var testFile = TestFile.Create(imagePath);
@@ -494,6 +495,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Jpg
         [InlineData(TestImages.Jpeg.Baseline.Ycck, 32)]
         [InlineData(TestImages.Jpeg.Baseline.Jpeg400, 8)]
         [InlineData(TestImages.Jpeg.Baseline.Snake, 24)]
+        [InlineData(TestImages.Jpeg.Baseline.Jpeg420Exif, 24)]
         public void DetectPixelSizePdfJs(string imagePath, int expectedPixelSize)
         {
             var testFile = TestFile.Create(imagePath);

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

@@ -33,7 +33,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Jpg
         {
             var expecteColorSpace = (JpegColorSpace)expectedColorSpaceValue;
 
-            using (OrigJpegDecoderCore decoder = JpegFixture.ParseStream(imageFile, true))
+            using (OrigJpegDecoderCore decoder = JpegFixture.ParseStream(imageFile, false))
             {
                 Assert.Equal(expecteColorSpace, decoder.ColorSpace);
             }
@@ -42,11 +42,11 @@ namespace SixLabors.ImageSharp.Tests.Formats.Jpg
         [Fact]
         public void ComponentScalingIsCorrect_1ChannelJpeg()
         {
-            using (OrigJpegDecoderCore decoder = JpegFixture.ParseStream(TestImages.Jpeg.Baseline.Jpeg400, true))
+            using (OrigJpegDecoderCore decoder = JpegFixture.ParseStream(TestImages.Jpeg.Baseline.Jpeg400, false))
             {
                 Assert.Equal(1, decoder.ComponentCount);
                 Assert.Equal(1, decoder.Components.Length);
-                
+
                 Size expectedSizeInBlocks = decoder.ImageSizeInPixels.DivideRoundUp(8);
 
                 Assert.Equal(expectedSizeInBlocks, decoder.ImageSizeInMCU);
@@ -68,7 +68,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Jpg
         {
             var sb = new StringBuilder();
 
-            using (OrigJpegDecoderCore decoder = JpegFixture.ParseStream(imageFile, true))
+            using (OrigJpegDecoderCore decoder = JpegFixture.ParseStream(imageFile, false))
             {
                 sb.AppendLine(imageFile);
                 sb.AppendLine($"Size:{decoder.ImageSizeInPixels} MCU:{decoder.ImageSizeInMCU}");
@@ -103,23 +103,23 @@ namespace SixLabors.ImageSharp.Tests.Formats.Jpg
             Size fLuma = (Size)expectedLumaFactors;
             Size fChroma = (Size)expectedChromaFactors;
 
-            using (OrigJpegDecoderCore decoder = JpegFixture.ParseStream(imageFile, true))
+            using (OrigJpegDecoderCore decoder = JpegFixture.ParseStream(imageFile, false))
             {
                 Assert.Equal(componentCount, decoder.ComponentCount);
                 Assert.Equal(componentCount, decoder.Components.Length);
-                
+
                 OrigComponent c0 = decoder.Components[0];
                 OrigComponent c1 = decoder.Components[1];
                 OrigComponent c2 = decoder.Components[2];
 
                 var uniform1 = new Size(1, 1);
 
-                Size expectedLumaSizeInBlocks = decoder.ImageSizeInMCU.MultiplyBy(fLuma) ;
+                Size expectedLumaSizeInBlocks = decoder.ImageSizeInMCU.MultiplyBy(fLuma);
 
                 Size divisor = fLuma.DivideBy(fChroma);
 
                 Size expectedChromaSizeInBlocks = expectedLumaSizeInBlocks.DivideRoundUp(divisor);
-                
+
                 VerifyJpeg.VerifyComponent(c0, expectedLumaSizeInBlocks, fLuma, uniform1);
                 VerifyJpeg.VerifyComponent(c1, expectedChromaSizeInBlocks, fChroma, divisor);
                 VerifyJpeg.VerifyComponent(c2, expectedChromaSizeInBlocks, fChroma, divisor);