Implemented YccK encoding

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverter.CmykAvx.cs

@@ -49,6 +49,9 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components
             }
 
             public override void ConvertFromRgbInplace(in ComponentValues values, Span<float> rLane, Span<float> gLane, Span<float> bLane)
+                => ConvertFromRgbInplace(in values, this.MaximumValue, rLane, gLane, bLane);
+
+            public static void ConvertFromRgbInplace(in ComponentValues values, float maxValue, Span<float> rLane, Span<float> gLane, Span<float> bLane)
             {
                 ref Vector256<float> destC =
                     ref Unsafe.As<float, Vector256<float>>(ref MemoryMarshal.GetReference(values.Component0));
@@ -67,7 +70,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components
                     ref Unsafe.As<float, Vector256<float>>(ref MemoryMarshal.GetReference(bLane));
 
                 // Used for the color conversion
-                var scale = Vector256.Create(this.MaximumValue);
+                var scale = Vector256.Create(maxValue);
 
                 nint n = values.Component0.Length / Vector256<float>.Count;
                 for (nint i = 0; i < n; i++)

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverter.CmykVector.cs

@@ -49,6 +49,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components
                  => CmykScalar.ConvertToRgbInplace(values, this.MaximumValue);
 
             protected override void ConvertCoreVectorizedInplaceFromRgb(in ComponentValues values, Span<float> r, Span<float> g, Span<float> b)
+                => ConvertFromRgbInplaceVectorized(in values, this.MaximumValue, r, g, b);
+
+            protected override void ConvertCoreInplaceFromRgb(in ComponentValues values, Span<float> r, Span<float> g, Span<float> b)
+                => ConvertFromRgbInplaceRemainder(values, this.MaximumValue, r, g, b);
+
+            public static void ConvertFromRgbInplaceVectorized(in ComponentValues values, float maxValue, Span<float> r, Span<float> g, Span<float> b)
             {
                 ref Vector<float> destC =
                     ref Unsafe.As<float, Vector<float>>(ref MemoryMarshal.GetReference(values.Component0));
@@ -67,7 +73,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components
                     ref Unsafe.As<float, Vector<float>>(ref MemoryMarshal.GetReference(b));
 
                 // Used for the color conversion
-                var scale = new Vector<float>(this.MaximumValue);
+                var scale = new Vector<float>(maxValue);
 
                 nint n = values.Component0.Length / Vector<float>.Count;
                 for (nint i = 0; i < n; i++)
@@ -89,8 +95,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components
                 }
             }
 
-            protected override void ConvertCoreInplaceFromRgb(in ComponentValues values, Span<float> r, Span<float> g, Span<float> b)
-                => CmykScalar.ConvertFromRgbInplace(values, this.MaximumValue, r, g, b);
+            public static void ConvertFromRgbInplaceRemainder(in ComponentValues values, float maxValue, Span<float> r, Span<float> g, Span<float> b)
+                => CmykScalar.ConvertFromRgbInplace(values, maxValue, r, g, b);
         }
     }
 }

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverter.YCbCrScalar.cs

@@ -9,7 +9,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components
     {
         internal sealed class YCbCrScalar : JpegColorConverterScalar
         {
-            // TODO: comments, derived from ITU-T Rec. T.871
+            // derived from ITU-T Rec. T.871
             internal const float RCrMult = 1.402f;
             internal const float GCbMult = (float)(0.114 * 1.772 / 0.587);
             internal const float GCrMult = (float)(0.299 * 1.402 / 0.587);

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverter.YccKAvx.cs

@@ -78,8 +78,56 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components
                 }
             }
 
-            public override void ConvertFromRgbInplace(in ComponentValues values, Span<float> r, Span<float> g, Span<float> b)
-                => throw new NotImplementedException();
+            public override void ConvertFromRgbInplace(in ComponentValues values, Span<float> rLane, Span<float> gLane, Span<float> bLane)
+            {
+                // rgb -> cmyk
+                CmykAvx.ConvertFromRgbInplace(in values, this.MaximumValue, rLane, gLane, bLane);
+
+                // cmyk -> ycck
+                ref Vector256<float> destY =
+                    ref Unsafe.As<float, Vector256<float>>(ref MemoryMarshal.GetReference(values.Component0));
+                ref Vector256<float> destCb =
+                    ref Unsafe.As<float, Vector256<float>>(ref MemoryMarshal.GetReference(values.Component1));
+                ref Vector256<float> destCr =
+                    ref Unsafe.As<float, Vector256<float>>(ref MemoryMarshal.GetReference(values.Component2));
+
+                ref Vector256<float> srcR = ref destY;
+                ref Vector256<float> srcG = ref destCb;
+                ref Vector256<float> srcB = ref destCr;
+
+                // Used for the color conversion
+                var maxSampleValue = Vector256.Create(this.MaximumValue);
+
+                var chromaOffset = Vector256.Create(this.HalfValue);
+
+                var f0299 = Vector256.Create(0.299f);
+                var f0587 = Vector256.Create(0.587f);
+                var f0114 = Vector256.Create(0.114f);
+                var fn0168736 = Vector256.Create(-0.168736f);
+                var fn0331264 = Vector256.Create(-0.331264f);
+                var fn0418688 = Vector256.Create(-0.418688f);
+                var fn0081312F = Vector256.Create(-0.081312F);
+                var f05 = Vector256.Create(0.5f);
+
+                nint n = values.Component0.Length / Vector256<float>.Count;
+                for (nint i = 0; i < n; i++)
+                {
+                    Vector256<float> r = Avx.Subtract(maxSampleValue, Unsafe.Add(ref srcR, i));
+                    Vector256<float> g = Avx.Subtract(maxSampleValue, Unsafe.Add(ref srcG, i));
+                    Vector256<float> b = Avx.Subtract(maxSampleValue, Unsafe.Add(ref srcB, i));
+
+                    // y  =   0 + (0.299 * r) + (0.587 * g) + (0.114 * b)
+                    // cb = 128 - (0.168736 * r) - (0.331264 * g) + (0.5 * b)
+                    // cr = 128 + (0.5 * r) - (0.418688 * g) - (0.081312 * b)
+                    Vector256<float> y = HwIntrinsics.MultiplyAdd(HwIntrinsics.MultiplyAdd(Avx.Multiply(f0114, b), f0587, g), f0299, r);
+                    Vector256<float> cb = Avx.Add(chromaOffset, HwIntrinsics.MultiplyAdd(HwIntrinsics.MultiplyAdd(Avx.Multiply(f05, b), fn0331264, g), fn0168736, r));
+                    Vector256<float> cr = Avx.Add(chromaOffset, HwIntrinsics.MultiplyAdd(HwIntrinsics.MultiplyAdd(Avx.Multiply(fn0081312F, b), fn0418688, g), f05, r));
+
+                    Unsafe.Add(ref destY, i) = y;
+                    Unsafe.Add(ref destCb, i) = cb;
+                    Unsafe.Add(ref destCr, i) = cr;
+                }
+            }
         }
     }
 }

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverter.YccKScalar.cs

@@ -9,6 +9,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components
     {
         internal sealed class YccKScalar : JpegColorConverterScalar
         {
+            // derived from ITU-T Rec. T.871
+            internal const float RCrMult = 1.402f;
+            internal const float GCbMult = (float)(0.114 * 1.772 / 0.587);
+            internal const float GCrMult = (float)(0.299 * 1.402 / 0.587);
+            internal const float BCbMult = 1.772f;
+
             public YccKScalar(int precision)
                 : base(JpegColorSpace.Ycck, precision)
             {
@@ -17,6 +23,9 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components
             public override void ConvertToRgbInplace(in ComponentValues values)
                 => ConvertToRgpInplace(values, this.MaximumValue, this.HalfValue);
 
+            public override void ConvertFromRgbInplace(in ComponentValues values, Span<float> r, Span<float> g, Span<float> b)
+                => ConvertCoreInplaceFromRgb(values, this.HalfValue, this.MaximumValue, r, g, b);
+
             public static void ConvertToRgpInplace(in ComponentValues values, float maxValue, float halfValue)
             {
                 Span<float> c0 = values.Component0;
@@ -33,14 +42,37 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components
                     float cr = c2[i] - halfValue;
                     float scaledK = c3[i] * scale;
 
-                    c0[i] = (maxValue - MathF.Round(y + (1.402F * cr), MidpointRounding.AwayFromZero)) * scaledK;
-                    c1[i] = (maxValue - MathF.Round(y - (0.344136F * cb) - (0.714136F * cr), MidpointRounding.AwayFromZero)) * scaledK;
-                    c2[i] = (maxValue - MathF.Round(y + (1.772F * cb), MidpointRounding.AwayFromZero)) * scaledK;
+                    // r = y + (1.402F * cr);
+                    // g = y - (0.344136F * cb) - (0.714136F * cr);
+                    // b = y + (1.772F * cb);
+                    c0[i] = MathF.Round(y + (RCrMult * cr), MidpointRounding.AwayFromZero) * scaledK;
+                    c1[i] = MathF.Round(y - (GCbMult * cb) - (GCrMult * cr), MidpointRounding.AwayFromZero) * scaledK;
+                    c2[i] = MathF.Round(y + (BCbMult * cb), MidpointRounding.AwayFromZero) * scaledK;
                 }
             }
 
-            public override void ConvertFromRgbInplace(in ComponentValues values, Span<float> r, Span<float> g, Span<float> b)
-                => throw new NotImplementedException();
+            public static void ConvertCoreInplaceFromRgb(in ComponentValues values, float halfValue, float maxValue, Span<float> rLane, Span<float> gLane, Span<float> bLane)
+            {
+                // rgb -> cmyk
+                CmykScalar.ConvertFromRgbInplace(in values, maxValue, rLane, gLane, bLane);
+
+                // cmyk -> ycck
+                Span<float> c = values.Component0;
+                Span<float> m = values.Component1;
+                Span<float> y = values.Component2;
+
+                for (int i = 0; i < y.Length; i++)
+                {
+                    float r = maxValue - c[i];
+                    float g = maxValue - m[i];
+                    float b = maxValue - y[i];
+
+                    // k value is passed untouched from rgb -> cmyk conversion
+                    c[i] = (0.299f * r) + (0.587f * g) + (0.114f * b);
+                    m[i] = halfValue - (0.168736f * r) - (0.331264f * g) + (0.5f * b);
+                    y[i] = halfValue + (0.5f * r) - (0.418688f * g) - (0.081312f * b);
+                }
+            }
         }
     }
 }

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverter.YccKVector.cs

@@ -72,11 +72,63 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components
             protected override void ConvertCoreInplaceToRgb(in ComponentValues values) =>
                 YccKScalar.ConvertToRgpInplace(values, this.MaximumValue, this.HalfValue);
 
-            protected override void ConvertCoreVectorizedInplaceFromRgb(in ComponentValues values, Span<float> r, Span<float> g, Span<float> b)
-                => throw new System.NotImplementedException();
+            protected override void ConvertCoreVectorizedInplaceFromRgb(in ComponentValues values, Span<float> rLane, Span<float> gLane, Span<float> bLane)
+            {
+                // rgb -> cmyk
+                CmykVector.ConvertFromRgbInplaceVectorized(in values, this.MaximumValue, rLane, gLane, bLane);
+
+                // cmyk -> ycck
+                ref Vector<float> destY =
+                    ref Unsafe.As<float, Vector<float>>(ref MemoryMarshal.GetReference(values.Component0));
+                ref Vector<float> destCb =
+                    ref Unsafe.As<float, Vector<float>>(ref MemoryMarshal.GetReference(values.Component1));
+                ref Vector<float> destCr =
+                    ref Unsafe.As<float, Vector<float>>(ref MemoryMarshal.GetReference(values.Component2));
+
+                ref Vector<float> srcR = ref destY;
+                ref Vector<float> srcG = ref destCb;
+                ref Vector<float> srcB = ref destCr;
+
+                var maxSampleValue = new Vector<float>(this.MaximumValue);
+
+                var chromaOffset = new Vector<float>(this.HalfValue);
+
+                var rYMult = new Vector<float>(0.299f);
+                var gYMult = new Vector<float>(0.587f);
+                var bYMult = new Vector<float>(0.114f);
+
+                var rCbMult = new Vector<float>(0.168736f);
+                var gCbMult = new Vector<float>(0.331264f);
+                var bCbMult = new Vector<float>(0.5f);
+
+                var rCrMult = new Vector<float>(0.5f);
+                var gCrMult = new Vector<float>(0.418688f);
+                var bCrMult = new Vector<float>(0.081312f);
+
+                nint n = values.Component0.Length / Vector<float>.Count;
+                for (nint i = 0; i < n; i++)
+                {
+                    Vector<float> r = maxSampleValue - Unsafe.Add(ref srcR, i);
+                    Vector<float> g = maxSampleValue - Unsafe.Add(ref srcG, i);
+                    Vector<float> b = maxSampleValue - Unsafe.Add(ref srcB, i);
+
+                    // y  =   0 + (0.299 * r) + (0.587 * g) + (0.114 * b)
+                    // cb = 128 - (0.168736 * r) - (0.331264 * g) + (0.5 * b)
+                    // cr = 128 + (0.5 * r) - (0.418688 * g) - (0.081312 * b)
+                    Unsafe.Add(ref destY, i) = (rYMult * r) + (gYMult * g) + (bYMult * b);
+                    Unsafe.Add(ref destCb, i) = chromaOffset - (rCbMult * r) - (gCbMult * g) + (bCbMult * b);
+                    Unsafe.Add(ref destCr, i) = chromaOffset + (rCrMult * r) - (gCrMult * g) - (bCrMult * b);
+                }
+            }
 
             protected override void ConvertCoreInplaceFromRgb(in ComponentValues values, Span<float> r, Span<float> g, Span<float> b)
-                => throw new System.NotImplementedException();
+            {
+                // rgb -> cmyk
+                CmykScalar.ConvertFromRgbInplace(in values, this.MaximumValue, r, g, b);
+
+                // cmyk -> ycck
+                YccKScalar.ConvertCoreInplaceFromRgb(in values, this.HalfValue, this.MaximumValue, r, g, b);
+            }
         }
     }
 }

src/ImageSharp/Formats/Jpeg/Components/Encoder/EncodingConfigs/JpegFrameConfig.cs

@@ -38,5 +38,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder
         public int MaxHorizontalSamplingFactor { get; }
 
         public int MaxVerticalSamplingFactor { get; }
+
+        public byte? AdobeColorTransformMarkerFlag { get; set; } = null;
     }
 }

src/ImageSharp/Formats/Jpeg/JpegDecoderCore.cs

@@ -596,12 +596,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
                 case JpegColorSpace.Cmyk:
                     return JpegEncodingColor.Cmyk;
                 case JpegColorSpace.Ycck:
-
-                    // TODO: change this after YccK encoding is implemented
-                    // We are deliberately mapping YccK color space to Cmyk color space at metadata
-                    // level so encoder can fallback to cmyk color space from it.
-                    // YccK -> Cmyk is the closest conversion logically wise
-                    return JpegEncodingColor.Cmyk;
+                    return JpegEncodingColor.Ycck;
                 default:
                     return JpegEncodingColor.YCbCrRatio420;
             }

src/ImageSharp/Formats/Jpeg/JpegEncoderCore.cs

@@ -81,16 +81,16 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
             // Write the Start Of Image marker.
             this.WriteStartOfImage();
 
-            // Write APP0 marker for any non-RGB colorspace image.
-            if (frameConfig.EncodingColor != JpegEncodingColor.Rgb)
+            // Write APP0 marker
+            if (frameConfig.AdobeColorTransformMarkerFlag is null)
             {
                 this.WriteJfifApplicationHeader(metadata);
             }
 
-            // Else write App14 marker to indicate RGB color space.
+            // Write APP14 marker with adobe color extension
             else
             {
-                this.WriteApp14Marker();
+                this.WriteApp14Marker(frameConfig.AdobeColorTransformMarkerFlag.Value);
             }
 
             // Write Exif, XMP, ICC and IPTC profiles
@@ -207,7 +207,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
         /// <summary>
         /// Writes the APP14 marker to indicate the image is in RGB color space.
         /// </summary>
-        private void WriteApp14Marker()
+        private void WriteApp14Marker(byte colorTransform)
         {
             this.WriteMarkerHeader(JpegConstants.Markers.APP14, 2 + Components.Decoder.AdobeMarker.Length);
 
@@ -227,8 +227,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
             // Flags1
             BinaryPrimitives.WriteInt16BigEndian(this.buffer.AsSpan(9, 2), 0);
 
-            // Transform byte, 0 in combination with three components means the image is in RGB colorspace.
-            this.buffer[11] = 0;
+            // Color transform byte
+            this.buffer[11] = colorTransform;
 
             this.outputStream.Write(this.buffer.AsSpan(0, 12));
         }
@@ -840,7 +840,10 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
                     new JpegQuantizationTableConfig[]
                     {
                         defaultLuminanceQuantTable
-                    }),
+                    })
+                {
+                    AdobeColorTransformMarkerFlag = JpegConstants.Adobe.ColorTransformUnknown
+                },
 
                 // Cmyk
                 new JpegFrameConfig(
@@ -861,7 +864,34 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
                     new JpegQuantizationTableConfig[]
                     {
                         defaultLuminanceQuantTable
-                    }),
+                    })
+                {
+                    AdobeColorTransformMarkerFlag = JpegConstants.Adobe.ColorTransformUnknown,
+                },
+
+                // YccK
+                new JpegFrameConfig(
+                    JpegColorSpace.Ycck,
+                    JpegEncodingColor.Ycck,
+                    new JpegComponentConfig[]
+                    {
+                        new JpegComponentConfig(id: 1, hsf: 1, vsf: 1, quantIndex: 0, dcIndex: 0, acIndex: 0),
+                        new JpegComponentConfig(id: 2, hsf: 1, vsf: 1, quantIndex: 0, dcIndex: 0, acIndex: 0),
+                        new JpegComponentConfig(id: 3, hsf: 1, vsf: 1, quantIndex: 0, dcIndex: 0, acIndex: 0),
+                        new JpegComponentConfig(id: 4, hsf: 1, vsf: 1, quantIndex: 0, dcIndex: 0, acIndex: 0),
+                    },
+                    new JpegHuffmanTableConfig[]
+                    {
+                        defaultLuminanceHuffmanDC,
+                        defaultLuminanceHuffmanAC
+                    },
+                    new JpegQuantizationTableConfig[]
+                    {
+                        defaultLuminanceQuantTable
+                    })
+                {
+                    AdobeColorTransformMarkerFlag = JpegConstants.Adobe.ColorTransformYcck,
+                },
             };
         }
     }

src/ImageSharp/Formats/Jpeg/JpegEncodingColor.cs

@@ -54,5 +54,10 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
         /// CMYK colorspace (cyan, magenta, yellow, and key black) intended for printing.
         /// </summary>
         Cmyk = 7,
+
+        /// <summary>
+        /// YCCK colorspace (Y, Cb, Cr, and key black).
+        /// </summary>
+        Ycck = 8,
     }
 }