Begin simplifying forward color conversion

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

@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors.
+// Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
 using System.Runtime.CompilerServices;
@@ -96,7 +96,14 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder
         /// Optimized method to allocates the correct y, cb, and cr values to the DCT blocks from the given r, g, b values.
         /// </summary>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public void ConvertPixelInto(int r, int g, int b, ref float yResult, ref float cbResult, ref float crResult)
+        public void ConvertPixelInto(
+            int r,
+            int g,
+            int b,
+            ref Block8x8F yResult,
+            ref Block8x8F cbResult,
+            ref Block8x8F crResult,
+            int i)
         {
             ref int start = ref Unsafe.As<RgbToYCbCrTables, int>(ref this);
 
@@ -111,9 +118,9 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder
             ref int crG = ref Unsafe.Add(ref start, 256 * 6);
             ref int crB = ref Unsafe.Add(ref start, 256 * 7);
 
-            yResult = (Unsafe.Add(ref yR, r) + Unsafe.Add(ref yG, g) + Unsafe.Add(ref yB, b)) >> ScaleBits;
-            cbResult = (Unsafe.Add(ref cbR, r) + Unsafe.Add(ref cbG, g) + Unsafe.Add(ref cbB, b)) >> ScaleBits;
-            crResult = (Unsafe.Add(ref cbB, r) + Unsafe.Add(ref crG, g) + Unsafe.Add(ref crB, b)) >> ScaleBits;
+            yResult[i] = (Unsafe.Add(ref yR, r) + Unsafe.Add(ref yG, g) + Unsafe.Add(ref yB, b)) >> ScaleBits;
+            cbResult[i] = (Unsafe.Add(ref cbR, r) + Unsafe.Add(ref cbG, g) + Unsafe.Add(ref cbB, b)) >> ScaleBits;
+            crResult[i] = (Unsafe.Add(ref cbB, r) + Unsafe.Add(ref crG, g) + Unsafe.Add(ref crB, b)) >> ScaleBits;
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
@@ -122,4 +129,4 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder
             return (int)((x * (1L << ScaleBits)) + 0.5F);
         }
     }
-}
+}

src/ImageSharp/Formats/Jpeg/Components/Encoder/YCbCrForwardConverter{TPixel}.cs

@@ -62,9 +62,9 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder
             Span<Rgb24> rgbSpan = this.rgbBlock.AsSpanUnsafe();
             PixelOperations<TPixel>.Instance.ToRgb24(frame.GetConfiguration(), this.pixelBlock.AsSpanUnsafe(), rgbSpan);
 
-            ref float yBlockStart = ref Unsafe.As<Block8x8F, float>(ref this.Y);
-            ref float cbBlockStart = ref Unsafe.As<Block8x8F, float>(ref this.Cb);
-            ref float crBlockStart = ref Unsafe.As<Block8x8F, float>(ref this.Cr);
+            ref Block8x8F yBlock = ref this.Y;
+            ref Block8x8F cbBlock = ref this.Cb;
+            ref Block8x8F crBlock = ref this.Cr;
             ref Rgb24 rgbStart = ref rgbSpan[0];
 
             for (int i = 0; i < 64; i++)
@@ -75,9 +75,10 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder
                     c.R,
                     c.G,
                     c.B,
-                    ref Unsafe.Add(ref yBlockStart, i),
-                    ref Unsafe.Add(ref cbBlockStart, i),
-                    ref Unsafe.Add(ref crBlockStart, i));
+                    ref yBlock,
+                    ref cbBlock,
+                    ref crBlock,
+                    i);
             }
         }
     }