Re-Introduce TiffBitsPerSample

src/ImageSharp/Formats/Tiff/Constants/TiffConstants.cs

@@ -85,16 +85,46 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Constants
         /// </summary>
         public static readonly ushort[] BitsPerSample1Bit = { 1 };
 
+        /// <summary>
+        /// The bits per sample for images with a 2 color palette.
+        /// </summary>
+        public static readonly ushort[] BitsPerSample2Bit = { 2 };
+
         /// <summary>
         /// The bits per sample for images with a 4 color palette.
         /// </summary>
         public static readonly ushort[] BitsPerSample4Bit = { 4 };
 
+        /// <summary>
+        /// The bits per sample for 6 bit gray images.
+        /// </summary>
+        public static readonly ushort[] BitsPerSample6Bit = { 6 };
+
         /// <summary>
         /// The bits per sample for 8 bit images.
         /// </summary>
         public static readonly ushort[] BitsPerSample8Bit = { 8 };
 
+        /// <summary>
+        /// The bits per sample for 10 bit gray images.
+        /// </summary>
+        public static readonly ushort[] BitsPerSample10Bit = { 10 };
+
+        /// <summary>
+        /// The bits per sample for 12 bit gray images.
+        /// </summary>
+        public static readonly ushort[] BitsPerSample12Bit = { 12 };
+
+        /// <summary>
+        /// The bits per sample for 14 bit gray images.
+        /// </summary>
+        public static readonly ushort[] BitsPerSample14Bit = { 14 };
+
+        /// <summary>
+        /// The bits per sample for 16 bit gray images.
+        /// </summary>
+        public static readonly ushort[] BitsPerSample16Bit = { 16 };
+
         /// <summary>
         /// The bits per sample for color images with 2 bits for each color channel.
         /// </summary>
@@ -115,11 +145,21 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Constants
         /// </summary>
         public static readonly ushort[] BitsPerSampleRgb10Bit = { 10, 10, 10 };
 
+        /// <summary>
+        /// The bits per sample for color images with 12 bits for each color channel.
+        /// </summary>
+        public static readonly ushort[] BitsPerSampleRgb12Bit = { 12, 12, 12 };
+
         /// <summary>
         /// The bits per sample for color images with 14 bits for each color channel.
         /// </summary>
         public static readonly ushort[] BitsPerSampleRgb14Bit = { 14, 14, 14 };
 
+        /// <summary>
+        /// The bits per sample for color images with 14 bits for each color channel.
+        /// </summary>
+        public static readonly ushort[] BitsPerSampleRgb16Bit = { 16, 16, 16 };
+
         /// <summary>
         /// The list of mimetypes that equate to a tiff.
         /// </summary>

src/ImageSharp/Formats/Tiff/TiffBitsPerSample.cs

@@ -0,0 +1,96 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+namespace SixLabors.ImageSharp.Formats.Tiff
+{
+    /// <summary>
+    /// The number of bits per component.
+    /// </summary>
+    public enum TiffBitsPerSample
+    {
+        /// <summary>
+        /// The bits per samples is not known.
+        /// </summary>
+        Unknown = 0,
+
+        /// <summary>
+        /// One bit per sample for bicolor images.
+        /// </summary>
+        Bit1,
+
+        /// <summary>
+        /// Two bits per sample for grayscale images with 4 different levels of gray or paletted images with a palette of 4 colors.
+        /// </summary>
+        Bit2,
+
+        /// <summary>
+        /// Four bits per sample for grayscale images with 16 different levels of gray or paletted images with a palette of 16 colors.
+        /// </summary>
+        Bit4,
+
+        /// <summary>
+        /// Six bits per sample for grayscale images.
+        /// </summary>
+        Bit6,
+
+        /// <summary>
+        /// Eight bits per sample for grayscale images with 256 different levels of gray or paletted images with a palette of 256 colors.
+        /// </summary>
+        Bit8,
+
+        /// <summary>
+        /// Ten bits per sample for grayscale images.
+        /// </summary>
+        Bit10,
+
+        /// <summary>
+        /// Twelve bits per sample for grayscale images.
+        /// </summary>
+        Bit12,
+
+        /// <summary>
+        /// Fourteen bits per sample for grayscale images.
+        /// </summary>
+        Bit14,
+
+        /// <summary>
+        /// Sixteen bits per sample for grayscale images.
+        /// </summary>
+        Bit16,
+
+        /// <summary>
+        /// 6 bits per sample, each channel has 2 bits.
+        /// </summary>
+        Rgb222,
+
+        /// <summary>
+        /// Twelve bits per sample, each channel has 4 bits.
+        /// </summary>
+        Rgb444,
+
+        /// <summary>
+        /// 24 bits per sample, each color channel has 8 Bits.
+        /// </summary>
+        Rgb888,
+
+        /// <summary>
+        /// Thirty bits per sample, each channel has 10 bits.
+        /// </summary>
+        Rgb101010,
+
+        /// <summary>
+        /// Thirty six bits per sample, each channel has 12 bits.
+        /// </summary>
+        Rgb121212,
+
+        /// <summary>
+        /// Forty two bits per sample, each channel has 14 bits.
+        /// </summary>
+        Rgb141414,
+
+        /// <summary>
+        /// Forty eight bits per sample, each channel has 16 bits.
+        /// </summary>
+        Rgb161616,
+    }
+}

src/ImageSharp/Formats/Tiff/TiffBitsPerSampleExtensions.cs

@@ -0,0 +1,170 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using SixLabors.ImageSharp.Formats.Tiff.Constants;
+
+namespace SixLabors.ImageSharp.Formats.Tiff
+{
+    internal static class TiffBitsPerSampleExtensions
+    {
+        /// <summary>
+        /// Gets the bits per channel array for a given BitsPerSample value, e,g, for RGB888: [8, 8, 8]
+        /// </summary>
+        /// <param name="tiffBitsPerSample">The tiff bits per sample.</param>
+        /// <returns>Bits per sample array.</returns>
+        public static ushort[] BitsPerChannel(this TiffBitsPerSample tiffBitsPerSample)
+        {
+            switch (tiffBitsPerSample)
+            {
+                case TiffBitsPerSample.Bit1:
+                    return TiffConstants.BitsPerSample1Bit;
+                case TiffBitsPerSample.Bit2:
+                    return TiffConstants.BitsPerSample2Bit;
+                case TiffBitsPerSample.Bit4:
+                    return TiffConstants.BitsPerSample4Bit;
+                case TiffBitsPerSample.Bit6:
+                    return TiffConstants.BitsPerSample6Bit;
+                case TiffBitsPerSample.Bit8:
+                    return TiffConstants.BitsPerSample8Bit;
+                case TiffBitsPerSample.Bit10:
+                    return TiffConstants.BitsPerSample10Bit;
+                case TiffBitsPerSample.Bit12:
+                    return TiffConstants.BitsPerSample12Bit;
+                case TiffBitsPerSample.Bit14:
+                    return TiffConstants.BitsPerSample14Bit;
+                case TiffBitsPerSample.Bit16:
+                    return TiffConstants.BitsPerSample16Bit;
+                case TiffBitsPerSample.Rgb222:
+                    return TiffConstants.BitsPerSampleRgb2Bit;
+                case TiffBitsPerSample.Rgb444:
+                    return TiffConstants.BitsPerSampleRgb4Bit;
+                case TiffBitsPerSample.Rgb888:
+                    return TiffConstants.BitsPerSampleRgb8Bit;
+                case TiffBitsPerSample.Rgb101010:
+                    return TiffConstants.BitsPerSampleRgb10Bit;
+                case TiffBitsPerSample.Rgb121212:
+                    return TiffConstants.BitsPerSampleRgb12Bit;
+                case TiffBitsPerSample.Rgb141414:
+                    return TiffConstants.BitsPerSampleRgb14Bit;
+                case TiffBitsPerSample.Rgb161616:
+                    return TiffConstants.BitsPerSampleRgb16Bit;
+                default:
+                    return Array.Empty<ushort>();
+            }
+        }
+
+        /// <summary>
+        /// Maps an array of bits per sample to a concrete enum value.
+        /// </summary>
+        /// <param name="bitsPerSample">The bits per sample array.</param>
+        /// <returns>TiffBitsPerSample enum value.</returns>
+        public static TiffBitsPerSample GetBitsPerSample(this ushort[] bitsPerSample)
+        {
+            switch (bitsPerSample.Length)
+            {
+                case 3:
+                    if (bitsPerSample[2] == TiffConstants.BitsPerSampleRgb16Bit[2] &&
+                        bitsPerSample[1] == TiffConstants.BitsPerSampleRgb16Bit[1] &&
+                        bitsPerSample[0] == TiffConstants.BitsPerSampleRgb16Bit[0])
+                    {
+                        return TiffBitsPerSample.Rgb161616;
+                    }
+
+                    if (bitsPerSample[2] == TiffConstants.BitsPerSampleRgb14Bit[2] &&
+                        bitsPerSample[1] == TiffConstants.BitsPerSampleRgb14Bit[1] &&
+                        bitsPerSample[0] == TiffConstants.BitsPerSampleRgb14Bit[0])
+                    {
+                        return TiffBitsPerSample.Rgb141414;
+                    }
+
+                    if (bitsPerSample[2] == TiffConstants.BitsPerSampleRgb12Bit[2] &&
+                        bitsPerSample[1] == TiffConstants.BitsPerSampleRgb12Bit[1] &&
+                        bitsPerSample[0] == TiffConstants.BitsPerSampleRgb12Bit[0])
+                    {
+                        return TiffBitsPerSample.Rgb121212;
+                    }
+
+                    if (bitsPerSample[2] == TiffConstants.BitsPerSampleRgb10Bit[2] &&
+                        bitsPerSample[1] == TiffConstants.BitsPerSampleRgb10Bit[1] &&
+                        bitsPerSample[0] == TiffConstants.BitsPerSampleRgb10Bit[0])
+                    {
+                        return TiffBitsPerSample.Rgb101010;
+                    }
+
+                    if (bitsPerSample[2] == TiffConstants.BitsPerSampleRgb8Bit[2] &&
+                        bitsPerSample[1] == TiffConstants.BitsPerSampleRgb8Bit[1] &&
+                        bitsPerSample[0] == TiffConstants.BitsPerSampleRgb8Bit[0])
+                    {
+                        return TiffBitsPerSample.Rgb888;
+                    }
+
+                    if (bitsPerSample[2] == TiffConstants.BitsPerSampleRgb4Bit[2] &&
+                        bitsPerSample[1] == TiffConstants.BitsPerSampleRgb4Bit[1] &&
+                        bitsPerSample[0] == TiffConstants.BitsPerSampleRgb4Bit[0])
+                    {
+                        return TiffBitsPerSample.Rgb444;
+                    }
+
+                    if (bitsPerSample[2] == TiffConstants.BitsPerSampleRgb2Bit[2] &&
+                        bitsPerSample[1] == TiffConstants.BitsPerSampleRgb2Bit[1] &&
+                        bitsPerSample[0] == TiffConstants.BitsPerSampleRgb2Bit[0])
+                    {
+                        return TiffBitsPerSample.Rgb222;
+                    }
+
+                    break;
+
+                case 1:
+                    if (bitsPerSample[0] == TiffConstants.BitsPerSample1Bit[0])
+                    {
+                        return TiffBitsPerSample.Bit1;
+                    }
+
+                    if (bitsPerSample[0] == TiffConstants.BitsPerSample2Bit[0])
+                    {
+                        return TiffBitsPerSample.Bit2;
+                    }
+
+                    if (bitsPerSample[0] == TiffConstants.BitsPerSample4Bit[0])
+                    {
+                        return TiffBitsPerSample.Bit4;
+                    }
+
+                    if (bitsPerSample[0] == TiffConstants.BitsPerSample6Bit[0])
+                    {
+                        return TiffBitsPerSample.Bit6;
+                    }
+
+                    if (bitsPerSample[0] == TiffConstants.BitsPerSample8Bit[0])
+                    {
+                        return TiffBitsPerSample.Bit8;
+                    }
+
+                    if (bitsPerSample[0] == TiffConstants.BitsPerSample10Bit[0])
+                    {
+                        return TiffBitsPerSample.Bit10;
+                    }
+
+                    if (bitsPerSample[0] == TiffConstants.BitsPerSample12Bit[0])
+                    {
+                        return TiffBitsPerSample.Bit12;
+                    }
+
+                    if (bitsPerSample[0] == TiffConstants.BitsPerSample14Bit[0])
+                    {
+                        return TiffBitsPerSample.Bit14;
+                    }
+
+                    if (bitsPerSample[0] == TiffConstants.BitsPerSample16Bit[0])
+                    {
+                        return TiffBitsPerSample.Bit16;
+                    }
+
+                    break;
+            }
+
+            return TiffBitsPerSample.Unknown;
+        }
+    }
+}

src/ImageSharp/Formats/Tiff/TiffDecoderOptionsParser.cs

@@ -69,7 +69,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
             options.Predictor = frameMetadata.Predictor ?? TiffPredictor.None;
             options.PhotometricInterpretation = frameMetadata.PhotometricInterpretation ?? TiffPhotometricInterpretation.Rgb;
             options.BitsPerPixel = frameMetadata.BitsPerPixel != null ? (int)frameMetadata.BitsPerPixel.Value : (int)TiffBitsPerPixel.Bit24;
-            options.BitsPerSample = frameMetadata.BitsPerSample ?? Array.Empty<ushort>();
+            options.BitsPerSample = frameMetadata.BitsPerSample != null ? frameMetadata.BitsPerSample?.BitsPerChannel() : Array.Empty<ushort>();
 
             options.ParseColorType(exifProfile);
             options.ParseCompression(frameMetadata.Compression, exifProfile);

src/ImageSharp/Formats/Tiff/TiffFrameMetadata.cs

@@ -38,7 +38,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         /// <summary>
         /// Gets or sets number of bits per component.
         /// </summary>
-        public ushort[] BitsPerSample { get; set; }
+        public TiffBitsPerSample? BitsPerSample { get; set; }
 
         /// <summary>
         /// Gets or sets the compression scheme used on the image data.
@@ -77,11 +77,10 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         {
             if (profile != null)
             {
-                meta.BitsPerSample = profile.GetValue(ExifTag.BitsPerSample)?.Value;
-                meta.BitsPerPixel = BitsPerPixelFromBitsPerSample(meta.BitsPerSample);
+                meta.BitsPerSample = profile.GetValue(ExifTag.BitsPerSample) != null ? profile.GetValue(ExifTag.BitsPerSample)?.Value.GetBitsPerSample() : null;
+                meta.BitsPerPixel = BitsPerPixelFromBitsPerSample(meta.BitsPerSample?.BitsPerChannel());
                 meta.Compression = (TiffCompression?)profile.GetValue(ExifTag.Compression)?.Value;
-                meta.PhotometricInterpretation =
-                    (TiffPhotometricInterpretation?)profile.GetValue(ExifTag.PhotometricInterpretation)?.Value;
+                meta.PhotometricInterpretation = (TiffPhotometricInterpretation?)profile.GetValue(ExifTag.PhotometricInterpretation)?.Value;
                 meta.Predictor = (TiffPredictor?)profile.GetValue(ExifTag.Predictor)?.Value;
 
                 profile.RemoveValue(ExifTag.BitsPerSample);

tests/ImageSharp.Tests/TestImages.cs

@@ -558,8 +558,6 @@ namespace SixLabors.ImageSharp.Tests
             public const string RgbPalette = "Tiff/rgb_palette.tiff";
             public const string Rgb4BitPalette = "Tiff/bike_colorpalette_4bit.tiff";
             public const string RgbPaletteDeflate = "Tiff/rgb_palette_deflate.tiff";
-            public const string Flower4BitPalette = "Tiff/flower-palette-04.tiff";
-            public const string Flower4BitPaletteGray = "Tiff/flower-minisblack-04.tiff";
             public const string FlowerRgb161616Contiguous = "Tiff/flower-rgb-contig-16.tiff";
             public const string FlowerRgb161616Planar = "Tiff/flower-rgb-planar-16.tiff";
             public const string FlowerRgb141414Contiguous = "Tiff/flower-rgb-contig-14.tiff";
@@ -573,6 +571,8 @@ namespace SixLabors.ImageSharp.Tests
             public const string FlowerRgb222Planar = "Tiff/flower-rgb-planar-02.tiff";
             public const string Flower2BitGray = "Tiff/flower-minisblack-02.tiff";
             public const string Flower2BitPalette = "Tiff/flower-palette-02.tiff";
+            public const string Flower4BitPalette = "Tiff/flower-palette-04.tiff";
+            public const string Flower4BitPaletteGray = "Tiff/flower-minisblack-04.tiff";
             public const string Flower6BitGray = "Tiff/flower-minisblack-06.tiff";
             public const string Flower8BitGray = "Tiff/flower-minisblack-08.tiff";
             public const string Flower10BitGray = "Tiff/flower-minisblack-10.tiff";