Add test

src/ImageSharp/Formats/Tiff/TiffEncoderCore.cs

@@ -155,7 +155,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
             Image<TPixel> metadataImage = image;
             foreach (ImageFrame<TPixel> frame in image.Frames)
             {
-                var subfileType = (TiffNewSubfileType)(frame.Metadata.ExifProfile.GetValue(ExifTag.SubfileType)?.Value ?? 0);
+                var subfileType = (TiffNewSubfileType)(frame.Metadata.ExifProfile?.GetValue(ExifTag.SubfileType)?.Value ?? (int)TiffNewSubfileType.FullImage);
 
                 if (subfileType != TiffNewSubfileType.FullImage)
                 {

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

@@ -18,7 +18,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Tiff
     [Trait("Format", "Tiff")]
     public abstract class TiffEncoderBaseTester
     {
-        private static readonly IImageDecoder ReferenceDecoder = new MagickReferenceDecoder();
+        protected static readonly IImageDecoder ReferenceDecoder = new MagickReferenceDecoder();
 
         protected static void TestStripLength<TPixel>(
             TestImageProvider<TPixel> provider,

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

@@ -2,10 +2,12 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
+using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.Formats.Tiff;
 using SixLabors.ImageSharp.Formats.Tiff.Constants;
 using SixLabors.ImageSharp.PixelFormats;
-
+using SixLabors.ImageSharp.Processing;
+using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison;
 using Xunit;
 
 using static SixLabors.ImageSharp.Tests.TestImages.Tiff;
@@ -13,6 +15,7 @@ using static SixLabors.ImageSharp.Tests.TestImages.Tiff;
 namespace SixLabors.ImageSharp.Tests.Formats.Tiff
 {
     [Trait("Format", "Tiff")]
+    [Trait("Format", "Tiff.m")]
     public class TiffEncoderMultiframeTests : TiffEncoderBaseTester
     {
         [Theory]
@@ -21,10 +24,40 @@ namespace SixLabors.ImageSharp.Tests.Formats.Tiff
             where TPixel : unmanaged, IPixel<TPixel> => TestTiffEncoderCore(provider, TiffBitsPerPixel.Bit24, TiffPhotometricInterpretation.Rgb);
 
         [Theory]
-        [WithFile(MultiframeDeflateWithPreview, PixelTypes.Rgba32)]
         [WithFile(MultiframeDifferentSize, PixelTypes.Rgba32)]
         [WithFile(MultiframeDifferentVariants, PixelTypes.Rgba32)]
         public void TiffEncoder_EncodeMultiframe_NotSupport<TPixel>(TestImageProvider<TPixel> provider)
             where TPixel : unmanaged, IPixel<TPixel> => Assert.Throws<NotSupportedException>(() => TestTiffEncoderCore(provider, TiffBitsPerPixel.Bit24, TiffPhotometricInterpretation.Rgb));
+
+        [Theory]
+        [WithFile(MultiframeDeflateWithPreview, PixelTypes.Rgba32)]
+        public void TiffEncoder_EncodeMultiframe_WithoutPreview_ProblemTest<TPixel>(TestImageProvider<TPixel> provider)
+        where TPixel : unmanaged, IPixel<TPixel> => Assert.Throws<ImagesSimilarityException>(() => TestTiffEncoderCore(provider, TiffBitsPerPixel.Bit24, TiffPhotometricInterpretation.Rgb));
+
+        [Theory]
+        [WithFile(RgbLzwNoPredictor, PixelTypes.Rgba32)]
+        public void TiffEncoder_EncodeMultiframe_Create<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            using var image = provider.GetImage();
+            using var image2 = new Image<Rgba32>(image.Width, image.Height, Color.Green.ToRgba32());
+
+            image.Frames.AddFrame(image2.Frames.RootFrame);
+
+            TiffBitsPerPixel bitsPerPixel = TiffBitsPerPixel.Bit24;
+            var encoder = new TiffEncoder
+            {
+                PhotometricInterpretation = TiffPhotometricInterpretation.Rgb,
+                BitsPerPixel = bitsPerPixel,
+                Compression = TiffCompression.Deflate
+            };
+
+            image.VerifyEncoder(
+                provider,
+                "tiff",
+                bitsPerPixel,
+                encoder,
+                ImageComparer.Exact);
+        }
     }
 }