Additional tests for decoding png's with filter

tests/ImageSharp.Benchmarks/Codecs/Png/DecodeFilteredPng.cs

@@ -23,9 +23,9 @@ namespace SixLabors.ImageSharp.Benchmarks.Codecs
         public void ReadImages()
         {
             this.filter0 = File.ReadAllBytes(TestImageFullPath(TestImages.Png.Filter0));
-            this.filter1 = File.ReadAllBytes(TestImageFullPath(TestImages.Png.Filter1));
-            this.filter2 = File.ReadAllBytes(TestImageFullPath(TestImages.Png.Filter2));
-            this.filter3 = File.ReadAllBytes(TestImageFullPath(TestImages.Png.Filter4));
+            this.filter1 = File.ReadAllBytes(TestImageFullPath(TestImages.Png.SubFilter3BytesPerPixel));
+            this.filter2 = File.ReadAllBytes(TestImageFullPath(TestImages.Png.UpFilter));
+            this.filter3 = File.ReadAllBytes(TestImageFullPath(TestImages.Png.PaethFilter3BytesPerPixel));
             this.averageFilter3bpp = File.ReadAllBytes(TestImageFullPath(TestImages.Png.AverageFilter3BytesPerPixel));
             this.averageFilter4bpp = File.ReadAllBytes(TestImageFullPath(TestImages.Png.AverageFilter4BytesPerPixel));
         }

tests/ImageSharp.Tests/Formats/Png/PngDecoderTests.cs

@@ -112,8 +112,8 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
         }
 
         [Theory]
-        [WithFile(TestImages.Png.AverageFilter3BytesPerPixel, PixelTypes.Rgba64)]
-        [WithFile(TestImages.Png.AverageFilter4BytesPerPixel, PixelTypes.Rgba64)]
+        [WithFile(TestImages.Png.AverageFilter3BytesPerPixel, PixelTypes.Rgba32)]
+        [WithFile(TestImages.Png.AverageFilter4BytesPerPixel, PixelTypes.Rgba32)]
         public void Decode_WithAverageFilter<TPixel>(TestImageProvider<TPixel> provider)
             where TPixel : unmanaged, IPixel<TPixel>
         {
@@ -122,6 +122,38 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
             image.CompareToOriginal(provider, ImageComparer.Exact);
         }
 
+        [Theory]
+        [WithFile(TestImages.Png.SubFilter3BytesPerPixel, PixelTypes.Rgba32)]
+        [WithFile(TestImages.Png.SubFilter4BytesPerPixel, PixelTypes.Rgba32)]
+        public void Decode_WithSubFilter<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            using Image<TPixel> image = provider.GetImage(PngDecoder);
+            image.DebugSave(provider);
+            image.CompareToOriginal(provider, ImageComparer.Exact);
+        }
+
+        [Theory]
+        [WithFile(TestImages.Png.UpFilter, PixelTypes.Rgba32)]
+        public void Decode_WithUpFilter<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            using Image<TPixel> image = provider.GetImage(PngDecoder);
+            image.DebugSave(provider);
+            image.CompareToOriginal(provider, ImageComparer.Exact);
+        }
+
+        [Theory]
+        [WithFile(TestImages.Png.PaethFilter3BytesPerPixel, PixelTypes.Rgba32)]
+        [WithFile(TestImages.Png.PaethFilter4BytesPerPixel, PixelTypes.Rgba32)]
+        public void Decode_WithPaethFilter<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            using Image<TPixel> image = provider.GetImage(PngDecoder);
+            image.DebugSave(provider);
+            image.CompareToOriginal(provider, ImageComparer.Exact);
+        }
+
         [Theory]
         [WithFile(TestImages.Png.GrayA8Bit, PixelTypes.Rgba32)]
         [WithFile(TestImages.Png.Gray1BitTrans, PixelTypes.Rgba32)]

tests/ImageSharp.Tests/TestImages.cs

@@ -66,12 +66,13 @@ namespace SixLabors.ImageSharp.Tests
 
             // Filtered test images from http://www.schaik.com/pngsuite/pngsuite_fil_png.html
             public const string Filter0 = "Png/filter0.png";
-            public const string Filter1 = "Png/filter1.png";
-            public const string Filter2 = "Png/filter2.png";
+            public const string SubFilter3BytesPerPixel = "Png/filter1.png";
+            public const string SubFilter4BytesPerPixel = "Png/SubFilter4Bpp.png";
+            public const string UpFilter = "Png/filter2.png";
             public const string AverageFilter3BytesPerPixel = "Png/filter3.png";
-            public const string Filter4 = "Png/filter4.png";
-
             public const string AverageFilter4BytesPerPixel = "Png/AverageFilter4Bpp.png";
+            public const string PaethFilter3BytesPerPixel = "Png/filter4.png";
+            public const string PaethFilter4BytesPerPixel = "Png/PaethFilter4Bpp.png";
 
             // Paletted images also from http://www.schaik.com/pngsuite/pngsuite_fil_png.html
             public const string PalettedTwoColor = "Png/basn3p01.png";
@@ -156,15 +157,6 @@ namespace SixLabors.ImageSharp.Tests
                 public const string ColorTypeOne = "Png/xc1n0g08.png";
                 public const string ColorTypeNine = "Png/xc9n2c08.png";
             }
-
-            public static readonly string[] All =
-            {
-                P1, Pd, Blur, Splash, Cross,
-                Powerpoint, SplashInterlaced, Interlaced,
-                Filter0, Filter1, Filter2, AverageFilter3BytesPerPixel, Filter4,
-                FilterVar, VimImage1, VimImage2, VersioningImage1,
-                VersioningImage2, Ratio4x1, Ratio1x4
-            };
         }
 
         public static class Jpeg

tests/Images/Input/Png/PaethFilter4Bpp.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:8b2b0a1190854577d5181fe40af61c421d615a1a2727cf9be5ebe727eaafd00d
+size 8624

tests/Images/Input/Png/SubFilter4Bpp.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:053fac72ff62c66dacb41a6251efa249d5b31567e0222efbf5b1bef912c0bf77
+size 13013