Set bits per pixel in tiff metadata

src/ImageSharp/Formats/Tiff/TiffBitsPerPixel.cs

@@ -0,0 +1,21 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+namespace SixLabors.ImageSharp.Formats.Tiff
+{
+    /// <summary>
+    /// Enumerates the available bits per pixel the tiff encoder supports.
+    /// </summary>
+    public enum TiffBitsPerPixel
+    {
+        /// <summary>
+        /// 8 bits per pixel. Each pixel consists of 1 byte.
+        /// </summary>
+        Pixel8 = 8,
+
+        /// <summary>
+        /// 24 bits per pixel. Each pixel consists of 3 bytes.
+        /// </summary>
+        Pixel24 = 24,
+    }
+}

src/ImageSharp/Formats/Tiff/TiffDecoderCore.cs

@@ -33,6 +33,19 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         /// </summary>
         private readonly bool ignoreMetadata;
 
+        /// <summary>
+        /// The image metadata.
+        /// </summary>
+        private ImageMetadata metadata;
+
+        /// <summary>
+        /// The tiff specific metadata.
+        /// </summary>
+        private TiffMetadata tiffMetaData;
+
+        /// <summary>
+        /// The stream to decode from.
+        /// </summary>
         private BufferedReadStream inputStream;
 
         /// <summary>
@@ -104,7 +117,9 @@ namespace SixLabors.ImageSharp.Formats.Tiff
                 framesMetadata.Add(frameMetadata);
             }
 
-            ImageMetadata metadata = framesMetadata.CreateMetadata(this.ignoreMetadata, tiffStream.ByteOrder);
+            this.metadata = framesMetadata.CreateMetadata(this.ignoreMetadata, tiffStream.ByteOrder);
+            this.tiffMetaData = this.metadata.GetTiffMetadata();
+            this.SetBitsPerPixel(framesMetadata);
 
             // todo: tiff frames can have different sizes
             {
@@ -119,11 +134,31 @@ namespace SixLabors.ImageSharp.Formats.Tiff
                 }
             }
 
-            var image = new Image<TPixel>(this.configuration, metadata, frames);
+            var image = new Image<TPixel>(this.configuration, this.metadata, frames);
 
             return image;
         }
 
+        private void SetBitsPerPixel(List<TiffFrameMetadata> framesMetadata)
+        {
+            TiffFrameMetadata firstMetaData = framesMetadata.First();
+            ushort[] bitsPerSample = firstMetaData.BitsPerSample;
+            var bitsPerPixel = 0;
+            foreach (var bps in bitsPerSample)
+            {
+                bitsPerPixel += bps;
+            }
+
+            if (bitsPerPixel == 24)
+            {
+                this.tiffMetaData.BitsPerPixel = TiffBitsPerPixel.Pixel24;
+            }
+            else if (bitsPerPixel == 8)
+            {
+                this.tiffMetaData.BitsPerPixel = TiffBitsPerPixel.Pixel8;
+            }
+        }
+
         /// <inheritdoc/>
         public IImageInfo Identify(BufferedReadStream stream, CancellationToken cancellationToken)
         {
@@ -168,7 +203,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
 
         private static TiffByteOrder ReadByteOrder(Stream stream)
         {
-            byte[] headerBytes = new byte[2];
+            var headerBytes = new byte[2];
             stream.Read(headerBytes, 0, 2);
             if (headerBytes[0] == TiffConstants.ByteOrderLittleEndian && headerBytes[1] == TiffConstants.ByteOrderLittleEndian)
             {
@@ -187,26 +222,26 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         /// </summary>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <param name="tags">The IFD tags.</param>
-        /// <param name="metadata">The frame metadata.</param>
+        /// <param name="frameMetaData">The frame metadata.</param>
         /// <returns>
         /// The tiff frame.
         /// </returns>
-        private ImageFrame<TPixel> DecodeFrame<TPixel>(IExifValue[] tags, out TiffFrameMetadata metadata)
+        private ImageFrame<TPixel> DecodeFrame<TPixel>(IExifValue[] tags, out TiffFrameMetadata frameMetaData)
             where TPixel : unmanaged, IPixel<TPixel>
         {
             var coreMetadata = new ImageFrameMetadata();
-            metadata = coreMetadata.GetTiffMetadata();
-            metadata.Tags = tags;
+            frameMetaData = coreMetadata.GetTiffMetadata();
+            frameMetaData.Tags = tags;
 
-            this.VerifyAndParseOptions(metadata);
+            this.VerifyAndParseOptions(frameMetaData);
 
-            int width = (int)metadata.Width;
-            int height = (int)metadata.Height;
+            int width = (int)frameMetaData.Width;
+            int height = (int)frameMetaData.Height;
             var frame = new ImageFrame<TPixel>(this.configuration, width, height, coreMetadata);
 
-            int rowsPerStrip = (int)metadata.RowsPerStrip;
-            uint[] stripOffsets = metadata.StripOffsets;
-            uint[] stripByteCounts = metadata.StripByteCounts;
+            int rowsPerStrip = (int)frameMetaData.RowsPerStrip;
+            uint[] stripOffsets = frameMetaData.StripOffsets;
+            uint[] stripByteCounts = frameMetaData.StripByteCounts;
 
             if (this.PlanarConfiguration == TiffPlanarConfiguration.Planar)
             {

src/ImageSharp/Formats/Tiff/TiffEncoderCore.cs

@@ -5,8 +5,10 @@ using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Threading;
+
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.Metadata;
 using SixLabors.ImageSharp.Metadata.Profiles.Exif;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -32,6 +34,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         /// </summary>
         private Configuration configuration;
 
+        /// <summary>
+        /// The color depth, in number of bits per pixel.
+        /// </summary>
+        private TiffBitsPerPixel? bitsPerPixel;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="TiffEncoderCore"/> class.
         /// </summary>
@@ -66,9 +73,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff
             Guard.NotNull(stream, nameof(stream));
 
             this.configuration = image.GetConfiguration();
+            ImageMetadata metadata = image.Metadata;
+            TiffMetadata tiffMetadata = metadata.GetTiffMetadata();
+            this.bitsPerPixel ??= tiffMetadata.BitsPerPixel;
 
-            // TODO: bits per pixel hardcoded to 24 for the start.
-            short bpp = 24;
+            short bpp = (short)this.bitsPerPixel;
             int bytesPerLine = 4 * (((image.Width * bpp) + 31) / 32);
             this.padding = bytesPerLine - (int)(image.Width * (bpp / 8F));
 

src/ImageSharp/Formats/Tiff/TiffMetadata.cs

@@ -1,9 +1,6 @@
 // Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
-using System.Collections;
-using System.Collections.Generic;
-
 namespace SixLabors.ImageSharp.Formats.Tiff
 {
     /// <summary>
@@ -26,6 +23,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         {
             this.ByteOrder = other.ByteOrder;
             this.XmpProfile = other.XmpProfile;
+            this.BitsPerPixel = other.BitsPerPixel;
         }
 
         /// <summary>
@@ -33,6 +31,11 @@ namespace SixLabors.ImageSharp.Formats.Tiff
         /// </summary>
         public TiffByteOrder ByteOrder { get; set; }
 
+        /// <summary>
+        /// Gets or sets the number of bits per pixel.
+        /// </summary>
+        public TiffBitsPerPixel BitsPerPixel { get; set; } = TiffBitsPerPixel.Pixel24;
+
         /// <summary>
         /// Gets or sets the XMP profile.
         /// </summary>