Improve performance tiff colors

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/BlackIsZero1TiffColor.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
+
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -25,6 +26,8 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Tiff
 
             int offset = 0;
 
+            var black = new Rgba32(0, 0, 0, 0xff);
+            var white = new Rgba32(0xff, 0xff, 0xff, 0xff);
             for (int y = top; y < top + height; y++)
             {
                 for (int x = left; x < left + width; x += 8)
@@ -35,9 +38,9 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Tiff
                     for (int shift = 0; shift < maxShift; shift++)
                     {
                         int bit = (b >> (7 - shift)) & 1;
-                        byte intensity = (bit == 1) ? (byte)255 : (byte)0;
 
-                        color.FromRgba32(new Rgba32(intensity, intensity, intensity, 255));
+                        color.FromRgba32(bit == 0 ? black : white);
+
                         pixels[x + shift, y] = color;
                     }
                 }

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/BlackIsZero4TiffColor.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
+
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -25,19 +26,24 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Tiff
             int offset = 0;
             bool isOddWidth = (width & 1) == 1;
 
+            var rgba = default(Rgba32);
             for (int y = top; y < top + height; y++)
             {
-                for (int x = left; x < left + width - 1; x += 2)
+                for (int x = left; x < left + width - 1;)
                 {
                     byte byteData = data[offset++];
 
                     byte intensity1 = (byte)(((byteData & 0xF0) >> 4) * 17);
-                    color.FromRgba32(new Rgba32(intensity1, intensity1, intensity1, 255));
-                    pixels[x, y] = color;
+                    rgba.PackedValue = (uint)(intensity1 | (intensity1 << 8) | (intensity1 << 16) | (0xff << 24));
+                    color.FromRgba32(rgba);
+
+                    pixels[x++, y] = color;
 
                     byte intensity2 = (byte)((byteData & 0x0F) * 17);
-                    color.FromRgba32(new Rgba32(intensity2, intensity2, intensity2, 255));
-                    pixels[x + 1, y] = color;
+                    rgba.PackedValue = (uint)(intensity2 | (intensity2 << 8) | (intensity2 << 16) | (0xff << 24));
+                    color.FromRgba32(rgba);
+
+                    pixels[x++, y] = color;
                 }
 
                 if (isOddWidth)
@@ -45,7 +51,9 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Tiff
                     byte byteData = data[offset++];
 
                     byte intensity1 = (byte)(((byteData & 0xF0) >> 4) * 17);
-                    color.FromRgba32(new Rgba32(intensity1, intensity1, intensity1, 255));
+                    rgba.PackedValue = (uint)(intensity1 | (intensity1 << 8) | (intensity1 << 16) | (0xff << 24));
+                    color.FromRgba32(rgba);
+
                     pixels[left + width - 1, y] = color;
                 }
             }

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/BlackIsZero8TiffColor.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
+
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -24,13 +25,16 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Tiff
 
             int offset = 0;
 
+            var rgba = default(Rgba32);
             for (int y = top; y < top + height; y++)
             {
                 for (int x = left; x < left + width; x++)
                 {
                     byte intensity = data[offset++];
 
-                    color.FromRgba32(new Rgba32(intensity, intensity, intensity, 255));
+                    rgba.PackedValue = (uint)(intensity | (intensity << 8) | (intensity << 16) | (0xff << 24));
+                    color.FromRgba32(rgba);
+
                     pixels[x, y] = color;
                 }
             }

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/PaletteTiffColor.cs

@@ -49,7 +49,7 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Tiff
         {
             var palette = new TPixel[colorCount];
 
-            int rOffset = 0;
+            const int rOffset = 0;
             int gOffset = colorCount;
             int bOffset = colorCount * 2;
 

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/Rgb888TiffColor.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
+
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -24,6 +25,7 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Tiff
 
             int offset = 0;
 
+            var rgba = default(Rgba32);
             for (int y = top; y < top + height; y++)
             {
                 Span<TPixel> pixelRow = pixels.GetRowSpan(y);
@@ -34,7 +36,9 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Tiff
                     byte g = data[offset++];
                     byte b = data[offset++];
 
-                    color.FromRgba32(new Rgba32(r, g, b, 255));
+                    rgba.PackedValue = (uint)(r | (g << 8) | (b << 16) | (0xff << 24));
+                    color.FromRgba32(rgba);
+
                     pixelRow[x] = color;
                 }
             }

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/WhiteIsZero1TiffColor.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
+
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -24,6 +25,8 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Tiff
 
             int offset = 0;
 
+            var black = new Rgba32(0, 0, 0, 0xff);
+            var white = new Rgba32(0xff, 0xff, 0xff, 0xff);
             for (int y = top; y < top + height; y++)
             {
                 for (int x = left; x < left + width; x += 8)
@@ -34,9 +37,9 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Tiff
                     for (int shift = 0; shift < maxShift; shift++)
                     {
                         int bit = (b >> (7 - shift)) & 1;
-                        byte intensity = (bit == 1) ? (byte)0 : (byte)255;
 
-                        color.FromRgba32(new Rgba32(intensity, intensity, intensity, 255));
+                        color.FromRgba32(bit == 0 ? white : black);
+
                         pixels[x + shift, y] = color;
                     }
                 }

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/WhiteIsZero4TiffColor.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
+
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -25,19 +26,24 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Tiff
             int offset = 0;
             bool isOddWidth = (width & 1) == 1;
 
+            var rgba = default(Rgba32);
             for (int y = top; y < top + height; y++)
             {
-                for (int x = left; x < left + width - 1; x += 2)
+                for (int x = left; x < left + width - 1;)
                 {
                     byte byteData = data[offset++];
 
                     byte intensity1 = (byte)((15 - ((byteData & 0xF0) >> 4)) * 17);
-                    color.FromRgba32(new Rgba32(intensity1, intensity1, intensity1, 255));
-                    pixels[x, y] = color;
+                    rgba.PackedValue = (uint)(intensity1 | (intensity1 << 8) | (intensity1 << 16) | (0xff << 24));
+                    color.FromRgba32(rgba);
+
+                    pixels[x++, y] = color;
 
                     byte intensity2 = (byte)((15 - (byteData & 0x0F)) * 17);
-                    color.FromRgba32(new Rgba32(intensity2, intensity2, intensity2, 255));
-                    pixels[x + 1, y] = color;
+                    rgba.PackedValue = (uint)(intensity2 | (intensity2 << 8) | (intensity2 << 16) | (0xff << 24));
+                    color.FromRgba32(rgba);
+
+                    pixels[x++, y] = color;
                 }
 
                 if (isOddWidth)
@@ -45,7 +51,9 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Tiff
                     byte byteData = data[offset++];
 
                     byte intensity1 = (byte)((15 - ((byteData & 0xF0) >> 4)) * 17);
-                    color.FromRgba32(new Rgba32(intensity1, intensity1, intensity1, 255));
+                    rgba.PackedValue = (uint)(intensity1 | (intensity1 << 8) | (intensity1 << 16) | (0xff << 24));
+                    color.FromRgba32(rgba);
+
                     pixels[left + width - 1, y] = color;
                 }
             }

src/ImageSharp/Formats/Tiff/PhotometricInterpretation/WhiteIsZero8TiffColor.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
+
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -24,13 +25,16 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Tiff
 
             int offset = 0;
 
+            var rgba = default(Rgba32);
             for (int y = top; y < top + height; y++)
             {
                 for (int x = left; x < left + width; x++)
                 {
                     byte intensity = (byte)(255 - data[offset++]);
 
-                    color.FromRgba32(new Rgba32(intensity, intensity, intensity, 255));
+                    rgba.PackedValue = (uint)(intensity | (intensity << 8) | (intensity << 16) | (0xff << 24));
+                    color.FromRgba32(rgba);
+
                     pixels[x, y] = color;
                 }
             }