Use pixel row span to access pixels

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/BlackIsZero16TiffColor{TPixel}.cs

@@ -32,6 +32,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
             var l16 = default(L16);
             for (int y = top; y < top + height; y++)
             {
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y);
                 if (this.isBigEndian)
                 {
                     for (int x = left; x < left + width; x++)
@@ -39,7 +40,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                         ushort intensity = TiffUtils.ConvertToShortBigEndian(data.Slice(offset, 2));
                         offset += 2;
 
-                        pixels[x, y] = TiffUtils.ColorFromL16(l16, intensity, color);
+                        pixelRow[x] = TiffUtils.ColorFromL16(l16, intensity, color);
                     }
                 }
                 else
@@ -49,7 +50,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                         ushort intensity = TiffUtils.ConvertToShortLittleEndian(data.Slice(offset, 2));
                         offset += 2;
 
-                        pixels[x, y] = TiffUtils.ColorFromL16(l16, intensity, color);
+                        pixelRow[x] = TiffUtils.ColorFromL16(l16, intensity, color);
                     }
                 }
             }

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/BlackIsZero8TiffColor{TPixel}.cs

@@ -2,7 +2,7 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
-
+using SixLabors.ImageSharp.Formats.Tiff.Utils;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -24,14 +24,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
             var l8 = default(L8);
             for (int y = top; y < top + height; y++)
             {
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y);
                 for (int x = left; x < left + width; x++)
                 {
                     byte intensity = data[offset++];
-
-                    l8.PackedValue = intensity;
-                    color.FromL8(l8);
-
-                    pixels[x, y] = color;
+                    pixelRow[x] = TiffUtils.ColorFromL8(l8, intensity, color);
                 }
             }
         }

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/BlackIsZeroTiffColor{TPixel}.cs

@@ -34,13 +34,14 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
 
             for (int y = top; y < top + height; y++)
             {
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y);
                 for (int x = left; x < left + width; x++)
                 {
                     int value = bitReader.ReadBits(this.bitsPerSample0);
                     float intensity = value / this.factor;
 
                     color.FromVector4(new Vector4(intensity, intensity, intensity, 1.0f));
-                    pixels[x, y] = color;
+                    pixelRow[x] = color;
                 }
 
                 bitReader.NextRow();

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/PaletteTiffColor{TPixel}.cs

@@ -35,10 +35,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
 
             for (int y = top; y < top + height; y++)
             {
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y);
                 for (int x = left; x < left + width; x++)
                 {
                     int index = bitReader.ReadBits(this.bitsPerSample0);
-                    pixels[x, y] = this.palette[index];
+                    pixelRow[x] = this.palette[index];
                 }
 
                 bitReader.NextRow();

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/Rgb16PlanarTiffColor{TPixel}.cs

@@ -35,6 +35,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
             var rgba = default(Rgba64);
             for (int y = top; y < top + height; y++)
             {
+                System.Span<TPixel> pixelRow = pixels.GetRowSpan(y);
                 if (this.isBigEndian)
                 {
                     for (int x = left; x < left + width; x++)
@@ -45,7 +46,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
 
                         offset += 2;
 
-                        pixels[x, y] = TiffUtils.ColorFromRgba64(rgba, r, g, b, color);
+                        pixelRow[x] = TiffUtils.ColorFromRgba64(rgba, r, g, b, color);
                     }
                 }
                 else
@@ -58,7 +59,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
 
                         offset += 2;
 
-                        pixels[x, y] = TiffUtils.ColorFromRgba64(rgba, r, g, b, color);
+                        pixelRow[x] = TiffUtils.ColorFromRgba64(rgba, r, g, b, color);
                     }
                 }
             }

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/RgbPlanarTiffColor{TPixel}.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
+using System;
 using System.Buffers;
 using System.Numerics;
 using SixLabors.ImageSharp.Formats.Tiff.Utils;
@@ -57,6 +58,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
 
             for (int y = top; y < top + height; y++)
             {
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y);
                 for (int x = left; x < left + width; x++)
                 {
                     float r = rBitReader.ReadBits(this.bitsPerSampleR) / this.rFactor;
@@ -64,7 +66,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                     float b = bBitReader.ReadBits(this.bitsPerSampleB) / this.bFactor;
 
                     color.FromVector4(new Vector4(r, g, b, 1.0f));
-                    pixels[x, y] = color;
+                    pixelRow[x] = color;
                 }
 
                 rBitReader.NextRow();

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/RgbTiffColor{TPixel}.cs

@@ -47,6 +47,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
 
             for (int y = top; y < top + height; y++)
             {
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y);
                 for (int x = left; x < left + width; x++)
                 {
                     float r = bitReader.ReadBits(this.bitsPerSampleR) / this.rFactor;
@@ -54,7 +55,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                     float b = bitReader.ReadBits(this.bitsPerSampleB) / this.bFactor;
 
                     color.FromVector4(new Vector4(r, g, b, 1.0f));
-                    pixels[x, y] = color;
+                    pixelRow[x] = color;
                 }
 
                 bitReader.NextRow();

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/WhiteIsZero16TiffColor{TPixel}.cs

@@ -32,6 +32,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
             var l16 = default(L16);
             for (int y = top; y < top + height; y++)
             {
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y);
                 if (this.isBigEndian)
                 {
                     for (int x = left; x < left + width; x++)
@@ -39,7 +40,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                         ushort intensity = (ushort)(ushort.MaxValue - TiffUtils.ConvertToShortBigEndian(data.Slice(offset, 2)));
                         offset += 2;
 
-                        pixels[x, y] = TiffUtils.ColorFromL16(l16, intensity, color);
+                        pixelRow[x] = TiffUtils.ColorFromL16(l16, intensity, color);
                     }
                 }
                 else
@@ -49,7 +50,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
                         ushort intensity = (ushort)(ushort.MaxValue - TiffUtils.ConvertToShortLittleEndian(data.Slice(offset, 2)));
                         offset += 2;
 
-                        pixels[x, y] = TiffUtils.ColorFromL16(l16, intensity, color);
+                        pixelRow[x] = TiffUtils.ColorFromL16(l16, intensity, color);
                     }
                 }
             }

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/WhiteIsZero8TiffColor{TPixel}.cs

@@ -2,7 +2,7 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
-
+using SixLabors.ImageSharp.Formats.Tiff.Utils;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -24,14 +24,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
             var l8 = default(L8);
             for (int y = top; y < top + height; y++)
             {
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y);
                 for (int x = left; x < left + width; x++)
                 {
                     byte intensity = (byte)(255 - data[offset++]);
-
-                    l8.PackedValue = intensity;
-                    color.FromL8(l8);
-
-                    pixels[x, y] = color;
+                    pixelRow[x] = TiffUtils.ColorFromL8(l8, intensity, color);
                 }
             }
         }

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/WhiteIsZeroTiffColor{TPixel}.cs

@@ -34,13 +34,14 @@ namespace SixLabors.ImageSharp.Formats.Tiff.PhotometricInterpretation
 
             for (int y = top; y < top + height; y++)
             {
+                Span<TPixel> pixelRow = pixels.GetRowSpan(y);
                 for (int x = left; x < left + width; x++)
                 {
                     int value = bitReader.ReadBits(this.bitsPerSample0);
                     float intensity = 1.0f - (value / this.factor);
 
                     color.FromVector4(new Vector4(intensity, intensity, intensity, 1.0f));
-                    pixels[x, y] = color;
+                    pixelRow[x] = color;
                 }
 
                 bitReader.NextRow();

src/ImageSharp/Formats/Tiff/Utils/TiffUtils.cs

@@ -21,6 +21,15 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Utils
         public static ushort ConvertToShortLittleEndian(ReadOnlySpan<byte> buffer) =>
             BinaryPrimitives.ReadUInt16LittleEndian(buffer);
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static TPixel ColorFromL8<TPixel>(L8 l8, byte intensity, TPixel color)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            l8.PackedValue = intensity;
+            color.FromL8(l8);
+            return color;
+        }
+
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static TPixel ColorFromL16<TPixel>(L16 l16, ushort intensity, TPixel color)
             where TPixel : unmanaged, IPixel<TPixel>