Add support for WhiteIsZero bilevel & 4-bit images

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

@@ -10,6 +10,16 @@ namespace ImageSharp.Formats.Tiff
     /// </summary>
     internal enum TiffColorType
     {
+        /// <summary>
+        /// Grayscale:  0 is imaged as white. The maximum value is imaged as black. Optimised implementation for bilevel images.
+        /// </summary>
+        WhiteIsZero1,
+
+        /// <summary>
+        /// Grayscale:  0 is imaged as white. The maximum value is imaged as black. Optimised implementation for 4-bit images.
+        /// </summary>
+        WhiteIsZero4,
+
         /// <summary>
         /// Grayscale:  0 is imaged as white. The maximum value is imaged as black. Optimised implementation for 8-bit images.
         /// </summary>

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

@@ -0,0 +1,53 @@
+// <copyright file="WhiteIsZero1TiffColor.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp.Formats.Tiff
+{
+    using System;
+    using System.Runtime.CompilerServices;
+    using ImageSharp;
+
+    /// <summary>
+    /// Implements the 'WhiteIsZero' photometric interpretation (optimised for bilevel images).
+    /// </summary>
+    internal static class WhiteIsZero1TiffColor
+    {
+        /// <summary>
+        /// Decodes pixel data using the current photometric interpretation.
+        /// </summary>
+        /// <typeparam name="TColor">The pixel format.</typeparam>
+        /// <param name="data">The buffer to read image data from.</param>
+        /// <param name="pixels">The image buffer to write pixels to.</param>
+        /// <param name="left">The x-coordinate of the left-hand side of the image block.</param>
+        /// <param name="top">The y-coordinate of the  top of the image block.</param>
+        /// <param name="width">The width of the image block.</param>
+        /// <param name="height">The height of the image block.</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static void Decode<TColor>(byte[] data, PixelAccessor<TColor> pixels, int left, int top, int width, int height)
+            where TColor : struct, IPixel<TColor>
+        {
+            TColor color = default(TColor);
+
+            uint offset = 0;
+
+            for (int y = top; y < top + height; y++)
+            {
+                for (int x = left; x < left + width; x += 8)
+                {
+                    byte b = data[offset++];
+                    int maxShift = Math.Min(left + width - x, 8);
+
+                    for (int shift = 0; shift < maxShift; shift++)
+                    {
+                        int bit = (b >> (7 - shift)) & 1;
+                        byte intensity = (bit == 1) ? (byte)0 : (byte)255;
+                        color.PackFromBytes(intensity, intensity, intensity, 255);
+                        pixels[x + shift, y] = color;
+                    }
+                }
+            }
+        }
+    }
+}

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

@@ -0,0 +1,61 @@
+// <copyright file="WhiteIsZero4TiffColor.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp.Formats.Tiff
+{
+    using System.Runtime.CompilerServices;
+    using ImageSharp;
+
+    /// <summary>
+    /// Implements the 'WhiteIsZero' photometric interpretation (optimised for 4-bit grayscale images).
+    /// </summary>
+    internal static class WhiteIsZero4TiffColor
+    {
+        /// <summary>
+        /// Decodes pixel data using the current photometric interpretation.
+        /// </summary>
+        /// <typeparam name="TColor">The pixel format.</typeparam>
+        /// <param name="data">The buffer to read image data from.</param>
+        /// <param name="pixels">The image buffer to write pixels to.</param>
+        /// <param name="left">The x-coordinate of the left-hand side of the image block.</param>
+        /// <param name="top">The y-coordinate of the  top of the image block.</param>
+        /// <param name="width">The width of the image block.</param>
+        /// <param name="height">The height of the image block.</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static void Decode<TColor>(byte[] data, PixelAccessor<TColor> pixels, int left, int top, int width, int height)
+            where TColor : struct, IPixel<TColor>
+        {
+            TColor color = default(TColor);
+
+            uint offset = 0;
+            bool isOddWidth = (width & 1) == 1;
+
+            for (int y = top; y < top + height; y++)
+            {
+                for (int x = left; x < left + width - 1; x += 2)
+                {
+                    byte byteData = data[offset++];
+
+                    byte intensity1 = (byte)((15 - ((byteData & 0xF0) >> 4)) * 17);
+                    color.PackFromBytes(intensity1, intensity1, intensity1, 255);
+                    pixels[x, y] = color;
+
+                    byte intensity2 = (byte)((15 - (byteData & 0x0F)) * 17);
+                    color.PackFromBytes(intensity2, intensity2, intensity2, 255);
+                    pixels[x + 1, y] = color;
+                }
+
+                if (isOddWidth)
+                {
+                    byte byteData = data[offset++];
+
+                    byte intensity1 = (byte)((15 - ((byteData & 0xF0) >> 4)) * 17);
+                    color.PackFromBytes(intensity1, intensity1, intensity1, 255);
+                    pixels[left + width - 1, y] = color;
+                }
+            }
+        }
+    }
+}

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

@@ -9,7 +9,7 @@ namespace ImageSharp.Formats.Tiff
     using ImageSharp;
 
     /// <summary>
-    /// Implements the 'WhiteIsZero' photometric interpretation (optimised for 8-bit  grayscale images).
+    /// Implements the 'WhiteIsZero' photometric interpretation (optimised for 8-bit grayscale images).
     /// </summary>
     internal static class WhiteIsZero8TiffColor
     {

src/ImageSharp/Formats/Tiff/TiffDecoderCore.cs

@@ -299,18 +299,38 @@ namespace ImageSharp.Formats
                         {
                             uint[] bitsPerSample = this.ReadUnsignedIntegerArray(ref bitsPerSampleEntry);
 
-                            if (bitsPerSample.Length == 1 && bitsPerSample[0] == 8)
+                            if (bitsPerSample.Length == 1)
                             {
-                                this.ColorType = TiffColorType.WhiteIsZero8;
-                            }
-                            else
-                            {
-                                throw new NotSupportedException("The specified TIFF bit-depth is not supported.");
+                                switch (bitsPerSample[0])
+                                {
+                                    case 8:
+                                        {
+                                            this.ColorType = TiffColorType.WhiteIsZero8;
+                                            break;
+                                        }
+
+                                    case 4:
+                                        {
+                                            this.ColorType = TiffColorType.WhiteIsZero4;
+                                            break;
+                                        }
+
+                                    case 1:
+                                        {
+                                            this.ColorType = TiffColorType.WhiteIsZero1;
+                                            break;
+                                        }
+
+                                    default:
+                                        {
+                                            throw new NotSupportedException("The specified TIFF bit-depth is not supported.");
+                                        }
+                                }
                             }
                         }
                         else
                         {
-                            throw new NotSupportedException("TIFF bilevel images are not supported.");
+                            this.ColorType = TiffColorType.WhiteIsZero1;
                         }
 
                         break;
@@ -331,6 +351,10 @@ namespace ImageSharp.Formats
         {
             switch (this.ColorType)
             {
+                case TiffColorType.WhiteIsZero1:
+                    return ((width + 7) / 8) * height;
+                case TiffColorType.WhiteIsZero4:
+                    return ((width + 1) / 2) * height;
                 case TiffColorType.WhiteIsZero8:
                     return width * height;
                 default:
@@ -373,6 +397,12 @@ namespace ImageSharp.Formats
         {
             switch (this.ColorType)
             {
+                case TiffColorType.WhiteIsZero1:
+                    WhiteIsZero1TiffColor.Decode(data, pixels, left, top, width, height);
+                    break;
+                case TiffColorType.WhiteIsZero4:
+                    WhiteIsZero4TiffColor.Decode(data, pixels, left, top, width, height);
+                    break;
                 case TiffColorType.WhiteIsZero8:
                     WhiteIsZero8TiffColor.Decode(data, pixels, left, top, width, height);
                     break;

tests/ImageSharp.Formats.Tiff.Tests/Formats/Tiff/PhotometricInterpretation/PhotometricInterpretationTestBase.cs

@@ -50,7 +50,8 @@ namespace ImageSharp.Tests
                 {
                     for (int x = 0; x < resultWidth; x++)
                     {
-                        Assert.Equal(expectedResult[y][x], pixels[x, y]);
+                        Assert.True(expectedResult[y][x] == pixels[x, y],
+                            $"Pixel ({x}, {y}) should be {expectedResult[y][x]} but was {pixels[x,y]}");
                     }
                 }
             }

tests/ImageSharp.Formats.Tiff.Tests/Formats/Tiff/PhotometricInterpretation/WhiteIsZero8TiffColorTests.cs

@@ -1,51 +0,0 @@
-// <copyright file="WhiteIsZero8TiffColorTests.cs" company="James Jackson-South">
-// Copyright (c) James Jackson-South and contributors.
-// Licensed under the Apache License, Version 2.0.
-// </copyright>
-
-namespace ImageSharp.Tests
-{
-    using System.Collections.Generic;
-    using Xunit;
-
-    using ImageSharp.Formats.Tiff;
-
-    public class WhiteIsZero8TiffColorTests : PhotometricInterpretationTestBase
-    {
-        private static Color Gray000 = new Color(255, 255, 255, 255);
-        private static Color Gray128 = new Color(127, 127, 127, 255);
-        private static Color Gray255 = new Color(0, 0, 0, 255);
-
-        private static byte[] GrayscaleBytes4x4 = new byte[] { 128, 255, 000, 255,
-                                                               255, 255, 255, 255,
-                                                               000, 128, 128, 255,
-                                                               255, 000, 255, 128 };
-
-        private static Color[][] GrayscaleResult4x4 = new[] { new[] { Gray128, Gray255, Gray000, Gray255 },
-                                                              new[] { Gray255, Gray255, Gray255, Gray255 },
-                                                              new[] { Gray000, Gray128, Gray128, Gray255 },
-                                                              new[] { Gray255, Gray000, Gray255, Gray128 }};
-
-        public static IEnumerable<object[]> DecodeData
-        {
-            get
-            {
-                yield return new object[] { GrayscaleBytes4x4, 0, 0, 4, 4, GrayscaleResult4x4 };
-                yield return new object[] { GrayscaleBytes4x4, 0, 0, 4, 4, Offset(GrayscaleResult4x4, 0, 0, 6, 6) };
-                yield return new object[] { GrayscaleBytes4x4, 1, 0, 4, 4, Offset(GrayscaleResult4x4, 1, 0, 6, 6) };
-                yield return new object[] { GrayscaleBytes4x4, 0, 1, 4, 4, Offset(GrayscaleResult4x4, 0, 1, 6, 6) };
-                yield return new object[] { GrayscaleBytes4x4, 1, 1, 4, 4, Offset(GrayscaleResult4x4, 1, 1, 6, 6) };
-            }
-        }
-
-        [Theory]
-        [MemberData(nameof(DecodeData))]
-        public void Decode_WritesPixelData(byte[] inputData, int left, int top, int width, int height, Color[][] expectedResult)
-        {
-            AssertDecode(expectedResult, pixels =>
-                {
-                    WhiteIsZero8TiffColor.Decode(inputData, pixels, left, top, width, height);
-                });
-        }
-    }
-}

tests/ImageSharp.Formats.Tiff.Tests/Formats/Tiff/PhotometricInterpretation/WhiteIsZeroTiffColorTests.cs

@@ -0,0 +1,152 @@
+// <copyright file="WhiteIsZeroTiffColorTests.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp.Tests
+{
+    using System.Collections.Generic;
+    using Xunit;
+
+    using ImageSharp.Formats.Tiff;
+
+    public class WhiteIsZeroTiffColorTests : PhotometricInterpretationTestBase
+    {
+        private static Color Gray000 = new Color(255, 255, 255, 255);
+        private static Color Gray128 = new Color(127, 127, 127, 255);
+        private static Color Gray255 = new Color(0, 0, 0, 255);
+        private static Color Gray0 = new Color(255, 255, 255, 255);
+        private static Color Gray8 = new Color(119, 119, 119, 255);
+        private static Color GrayF = new Color(0, 0, 0, 255);
+        private static Color Bit0 = new Color(255, 255, 255, 255);
+        private static Color Bit1 = new Color(0, 0, 0, 255);
+
+        private static byte[] Bilevel_Bytes4x4 = new byte[] { 0b01010000,
+                                                              0b11110000,
+                                                              0b01110000,
+                                                              0b10010000 };
+
+        private static Color[][] Bilevel_Result4x4 = new[] { new[] { Bit0, Bit1, Bit0, Bit1 },
+                                                             new[] { Bit1, Bit1, Bit1, Bit1 },
+                                                             new[] { Bit0, Bit1, Bit1, Bit1 },
+                                                             new[] { Bit1, Bit0, Bit0, Bit1 }};
+
+        private static byte[] Bilevel_Bytes12x4 = new byte[] { 0b01010101, 0b01010000,
+                                                               0b11111111, 0b11111111,
+                                                               0b01101001, 0b10100000,
+                                                               0b10010000, 0b01100000};
+
+        private static Color[][] Bilevel_Result12x4 = new[] { new[] { Bit0, Bit1, Bit0, Bit1, Bit0, Bit1, Bit0, Bit1, Bit0, Bit1, Bit0, Bit1 },
+                                                              new[] { Bit1, Bit1, Bit1, Bit1, Bit1, Bit1, Bit1, Bit1, Bit1, Bit1, Bit1, Bit1 },
+                                                              new[] { Bit0, Bit1, Bit1, Bit0, Bit1, Bit0, Bit0, Bit1, Bit1, Bit0, Bit1, Bit0 },
+                                                              new[] { Bit1, Bit0, Bit0, Bit1, Bit0, Bit0, Bit0, Bit0, Bit0, Bit1, Bit1, Bit0 }};
+
+        private static byte[] Grayscale4_Bytes4x4 = new byte[] { 0x8F, 0x0F,
+                                                                 0xFF, 0xFF,
+                                                                 0x08, 0x8F,
+                                                                 0xF0, 0xF8 };
+
+        private static Color[][] Grayscale4_Result4x4 = new[] { new[] { Gray8, GrayF, Gray0, GrayF },
+                                                                new[] { GrayF, GrayF, GrayF, GrayF },
+                                                                new[] { Gray0, Gray8, Gray8, GrayF },
+                                                                new[] { GrayF, Gray0, GrayF, Gray8 }};
+
+        private static byte[] Grayscale4_Bytes3x4 = new byte[] { 0x8F, 0x00,
+                                                                 0xFF, 0xF0,
+                                                                 0x08, 0x80,
+                                                                 0xF0, 0xF0 };
+
+        private static Color[][] Grayscale4_Result3x4 = new[] { new[] { Gray8, GrayF, Gray0 },
+                                                                new[] { GrayF, GrayF, GrayF },
+                                                                new[] { Gray0, Gray8, Gray8 },
+                                                                new[] { GrayF, Gray0, GrayF }};
+
+        private static byte[] Grayscale8_Bytes4x4 = new byte[] { 128, 255, 000, 255,
+                                                                 255, 255, 255, 255,
+                                                                 000, 128, 128, 255,
+                                                                 255, 000, 255, 128 };
+
+        private static Color[][] Grayscale8_Result4x4 = new[] { new[] { Gray128, Gray255, Gray000, Gray255 },
+                                                                new[] { Gray255, Gray255, Gray255, Gray255 },
+                                                                new[] { Gray000, Gray128, Gray128, Gray255 },
+                                                                new[] { Gray255, Gray000, Gray255, Gray128 }};
+
+        public static IEnumerable<object[]> Bilevel_Data
+        {
+            get
+            {
+                yield return new object[] { Bilevel_Bytes4x4, 1, 0, 0, 4, 4, Bilevel_Result4x4 };
+                yield return new object[] { Bilevel_Bytes4x4, 1, 0, 0, 4, 4, Offset(Bilevel_Result4x4, 0, 0, 6, 6) };
+                yield return new object[] { Bilevel_Bytes4x4, 1, 1, 0, 4, 4, Offset(Bilevel_Result4x4, 1, 0, 6, 6) };
+                yield return new object[] { Bilevel_Bytes4x4, 1, 0, 1, 4, 4, Offset(Bilevel_Result4x4, 0, 1, 6, 6) };
+                yield return new object[] { Bilevel_Bytes4x4, 1, 1, 1, 4, 4, Offset(Bilevel_Result4x4, 1, 1, 6, 6) };
+
+                yield return new object[] { Bilevel_Bytes12x4, 1, 0, 0, 12, 4, Bilevel_Result12x4 };
+                yield return new object[] { Bilevel_Bytes12x4, 1, 0, 0, 12, 4, Offset(Bilevel_Result12x4, 0, 0, 18, 6) };
+                yield return new object[] { Bilevel_Bytes12x4, 1, 1, 0, 12, 4, Offset(Bilevel_Result12x4, 1, 0, 18, 6) };
+                yield return new object[] { Bilevel_Bytes12x4, 1, 0, 1, 12, 4, Offset(Bilevel_Result12x4, 0, 1, 18, 6) };
+                yield return new object[] { Bilevel_Bytes12x4, 1, 1, 1, 12, 4, Offset(Bilevel_Result12x4, 1, 1, 18, 6) };
+            }
+        }
+
+        public static IEnumerable<object[]> Grayscale4_Data
+        {
+            get
+            {
+                yield return new object[] { Grayscale4_Bytes4x4, 4, 0, 0, 4, 4, Grayscale4_Result4x4 };
+                yield return new object[] { Grayscale4_Bytes4x4, 4, 0, 0, 4, 4, Offset(Grayscale4_Result4x4, 0, 0, 6, 6) };
+                yield return new object[] { Grayscale4_Bytes4x4, 4, 1, 0, 4, 4, Offset(Grayscale4_Result4x4, 1, 0, 6, 6) };
+                yield return new object[] { Grayscale4_Bytes4x4, 4, 0, 1, 4, 4, Offset(Grayscale4_Result4x4, 0, 1, 6, 6) };
+                yield return new object[] { Grayscale4_Bytes4x4, 4, 1, 1, 4, 4, Offset(Grayscale4_Result4x4, 1, 1, 6, 6) };
+
+                yield return new object[] { Grayscale4_Bytes3x4, 4, 0, 0, 3, 4, Grayscale4_Result3x4 };
+                yield return new object[] { Grayscale4_Bytes3x4, 4, 0, 0, 3, 4, Offset(Grayscale4_Result3x4, 0, 0, 6, 6) };
+                yield return new object[] { Grayscale4_Bytes3x4, 4, 1, 0, 3, 4, Offset(Grayscale4_Result3x4, 1, 0, 6, 6) };
+                yield return new object[] { Grayscale4_Bytes3x4, 4, 0, 1, 3, 4, Offset(Grayscale4_Result3x4, 0, 1, 6, 6) };
+                yield return new object[] { Grayscale4_Bytes3x4, 4, 1, 1, 3, 4, Offset(Grayscale4_Result3x4, 1, 1, 6, 6) };
+            }
+        }
+
+        public static IEnumerable<object[]> Grayscale8_Data
+        {
+            get
+            {
+                yield return new object[] { Grayscale8_Bytes4x4, 8, 0, 0, 4, 4, Grayscale8_Result4x4 };
+                yield return new object[] { Grayscale8_Bytes4x4, 8, 0, 0, 4, 4, Offset(Grayscale8_Result4x4, 0, 0, 6, 6) };
+                yield return new object[] { Grayscale8_Bytes4x4, 8, 1, 0, 4, 4, Offset(Grayscale8_Result4x4, 1, 0, 6, 6) };
+                yield return new object[] { Grayscale8_Bytes4x4, 8, 0, 1, 4, 4, Offset(Grayscale8_Result4x4, 0, 1, 6, 6) };
+                yield return new object[] { Grayscale8_Bytes4x4, 8, 1, 1, 4, 4, Offset(Grayscale8_Result4x4, 1, 1, 6, 6) };
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(Bilevel_Data))]
+        public void Decode_WritesPixelData_Bilevel(byte[] inputData, int bitsPerSample, int left, int top, int width, int height, Color[][] expectedResult)
+        {
+            AssertDecode(expectedResult, pixels =>
+                {
+                    WhiteIsZero1TiffColor.Decode(inputData, pixels, left, top, width, height);
+                });
+        }
+
+        [Theory]
+        [MemberData(nameof(Grayscale4_Data))]
+        public void Decode_WritesPixelData_4Bit(byte[] inputData, int bitsPerSample, int left, int top, int width, int height, Color[][] expectedResult)
+        {
+            AssertDecode(expectedResult, pixels =>
+                {
+                    WhiteIsZero4TiffColor.Decode(inputData, pixels, left, top, width, height);
+                });
+        }
+
+        [Theory]
+        [MemberData(nameof(Grayscale8_Data))]
+        public void Decode_WritesPixelData_8Bit(byte[] inputData, int bitsPerSample, int left, int top, int width, int height, Color[][] expectedResult)
+        {
+            AssertDecode(expectedResult, pixels =>
+                {
+                    WhiteIsZero8TiffColor.Decode(inputData, pixels, left, top, width, height);
+                });
+        }
+    }
+}

tests/ImageSharp.Formats.Tiff.Tests/Formats/Tiff/TiffDecoderImageTests.cs

@@ -178,6 +178,10 @@ namespace ImageSharp.Tests
         [Theory]
         [InlineData(false, TiffPhotometricInterpretation.WhiteIsZero, new[] { 8 }, TiffColorType.WhiteIsZero8)]
         [InlineData(true, TiffPhotometricInterpretation.WhiteIsZero, new[] { 8 }, TiffColorType.WhiteIsZero8)]
+        [InlineData(false, TiffPhotometricInterpretation.WhiteIsZero, new[] { 4 }, TiffColorType.WhiteIsZero4)]
+        [InlineData(true, TiffPhotometricInterpretation.WhiteIsZero, new[] { 4 }, TiffColorType.WhiteIsZero4)]
+        [InlineData(false, TiffPhotometricInterpretation.WhiteIsZero, new[] { 1 }, TiffColorType.WhiteIsZero1)]
+        [InlineData(true, TiffPhotometricInterpretation.WhiteIsZero, new[] { 1 }, TiffColorType.WhiteIsZero1)]
         public void ReadImageFormat_DeterminesCorrectColorImplementation(bool isLittleEndian, ushort photometricInterpretation, int[] bitsPerSample, int colorType)
         {
             Stream stream = CreateTiffGenIfd()
@@ -192,6 +196,23 @@ namespace ImageSharp.Tests
             Assert.Equal((TiffColorType)colorType, decoder.ColorType);
         }
 
+        [Theory]
+        [InlineData(false, TiffPhotometricInterpretation.WhiteIsZero, TiffColorType.WhiteIsZero1)]
+        [InlineData(true, TiffPhotometricInterpretation.WhiteIsZero, TiffColorType.WhiteIsZero1)]
+        public void ReadImageFormat_DeterminesCorrectColorImplementation_DefaultsToBilevel(bool isLittleEndian, ushort photometricInterpretation, int colorType)
+        {
+            Stream stream = CreateTiffGenIfd()
+                            .WithEntry(TiffGenEntry.Integer(TiffTags.PhotometricInterpretation, TiffType.Short, photometricInterpretation))
+                            .WithoutEntry(TiffTags.BitsPerSample)
+                            .ToStream(isLittleEndian);
+
+            TiffDecoderCore decoder = new TiffDecoderCore(stream, isLittleEndian, null, null);
+            TiffIfd ifd = decoder.ReadIfd(0);
+            decoder.ReadImageFormat(ifd);
+
+            Assert.Equal((TiffColorType)colorType, decoder.ColorType);
+        }
+
         // [Theory]
         // [InlineData(false, new[] { 8 }, TiffColorType.WhiteIsZero8)]
         // [InlineData(true, new[] { 8 }, TiffColorType.WhiteIsZero8)]
@@ -285,9 +306,14 @@ namespace ImageSharp.Tests
 
         [Theory]
         [InlineData(TiffColorType.WhiteIsZero8, 100, 80, 100 * 80)]
+        [InlineData(TiffColorType.WhiteIsZero4, 100, 80, 50 * 80)]
+        [InlineData(TiffColorType.WhiteIsZero4, 99, 80, 50 * 80)]
+        [InlineData(TiffColorType.WhiteIsZero1, 160, 80, 20 * 80)]
+        [InlineData(TiffColorType.WhiteIsZero1, 153, 80, 20 * 80)]
         public void CalculateImageBufferSize_ReturnsCorrectSize(ushort colorType, int width, int height, int expectedResult)
         {
             TiffDecoderCore decoder = new TiffDecoderCore(null, null);
+            decoder.ColorType = (TiffColorType)colorType;
 
             int bufferSize = decoder.CalculateImageBufferSize(width, height);