Merge pull request #2676 from GranPC/public-pr/blurhash

Implement Blurhash generation for images

.vscode/tasks.json

@@ -10,6 +10,16 @@
                 "${workspaceFolder}/Jellyfin.Server/Jellyfin.Server.csproj"
             ],
             "problemMatcher": "$msCompile"
+        },
+        {
+            "label": "api tests",
+            "command": "dotnet",
+            "type": "process",
+            "args": [
+                "test",
+                "${workspaceFolder}/tests/MediaBrowser.Api.Tests/MediaBrowser.Api.Tests.csproj"
+            ],
+            "problemMatcher": "$msCompile"
         }
     ]
 }

Emby.Drawing/ImageProcessor.cs

@@ -313,6 +313,27 @@ namespace Emby.Drawing
         public ImageDimensions GetImageDimensions(string path)
             => _imageEncoder.GetImageSize(path);
 
+        /// <inheritdoc />
+        public string GetImageBlurHash(string path)
+        {
+            var size = GetImageDimensions(path);
+            if (size.Width <= 0 || size.Height <= 0)
+            {
+                return string.Empty;
+            }
+
+            // We want tiles to be as close to square as possible, and to *mostly* keep under 16 tiles for performance.
+            // One tile is (width / xComp) x (height / yComp) pixels, which means that ideally yComp = xComp * height / width.
+            // See more at https://github.com/woltapp/blurhash/#how-do-i-pick-the-number-of-x-and-y-components
+            float xCompF = MathF.Sqrt(16.0f * size.Width / size.Height);
+            float yCompF = xCompF * size.Height / size.Width;
+
+            int xComp = Math.Min((int)xCompF + 1, 9);
+            int yComp = Math.Min((int)yCompF + 1, 9);
+
+            return _imageEncoder.GetImageBlurHash(xComp, yComp, path);
+        }
+
         /// <inheritdoc />
         public string GetImageCacheTag(BaseItem item, ItemImageInfo image)
             => (item.Path + image.DateModified.Ticks).GetMD5().ToString("N", CultureInfo.InvariantCulture);

Emby.Drawing/NullImageEncoder.cs

@@ -42,5 +42,11 @@ namespace Emby.Drawing
         {
             throw new NotImplementedException();
         }
+
+        /// <inheritdoc />
+        public string GetImageBlurHash(int xComp, int yComp, string path)
+        {
+            throw new NotImplementedException();
+        }
     }
 }

Emby.Server.Implementations/Data/SqliteItemRepository.cs

@@ -1141,24 +1141,24 @@ namespace Emby.Server.Implementations.Data
 
         public string ToValueString(ItemImageInfo image)
         {
-            var delimeter = "*";
+            const string Delimeter = "*";
 
-            var path = image.Path;
+            var path = image.Path ?? string.Empty;
-
+            var hash = image.BlurHash ?? string.Empty;
-            if (path == null)
-            {
-                path = string.Empty;
-            }
 
             return GetPathToSave(path) +
-                   delimeter +
+                   Delimeter +
                    image.DateModified.Ticks.ToString(CultureInfo.InvariantCulture) +
-                   delimeter +
+                   Delimeter +
                    image.Type +
-                   delimeter +
+                   Delimeter +
                    image.Width.ToString(CultureInfo.InvariantCulture) +
-                   delimeter +
+                   Delimeter +
-                   image.Height.ToString(CultureInfo.InvariantCulture);
+                   image.Height.ToString(CultureInfo.InvariantCulture) +
+                   Delimeter +
+                   // Replace delimiters with other characters.
+                   // This can be removed when we migrate to a proper DB.
+                   hash.Replace('*', '/').Replace('|', '\\');
         }
 
         public ItemImageInfo ItemImageInfoFromValueString(string value)
@@ -1192,6 +1192,11 @@ namespace Emby.Server.Implementations.Data
                     image.Width = width;
                     image.Height = height;
                 }
+
+                if (parts.Length >= 6)
+                {
+                    image.BlurHash = parts[5].Replace('/', '*').Replace('\\', '|');
+                }
             }
 
             return image;

Emby.Server.Implementations/Dto/DtoService.cs

@@ -605,7 +605,7 @@ namespace Emby.Server.Implementations.Dto
 
                 if (dictionary.TryGetValue(person.Name, out Person entity))
                 {
-                    baseItemPerson.PrimaryImageTag = GetImageCacheTag(entity, ImageType.Primary);
+                    baseItemPerson.PrimaryImageTag = GetTagAndFillBlurhash(dto, entity, ImageType.Primary);
                     baseItemPerson.Id = entity.Id.ToString("N", CultureInfo.InvariantCulture);
                     list.Add(baseItemPerson);
                 }
@@ -654,6 +654,70 @@ namespace Emby.Server.Implementations.Dto
             return _libraryManager.GetGenreId(name);
         }
 
+        private string GetTagAndFillBlurhash(BaseItemDto dto, BaseItem item, ImageType imageType, int imageIndex = 0)
+        {
+            var image = item.GetImageInfo(imageType, imageIndex);
+            if (image != null)
+            {
+                return GetTagAndFillBlurhash(dto, item, image);
+            }
+
+            return null;
+        }
+
+        private string GetTagAndFillBlurhash(BaseItemDto dto, BaseItem item, ItemImageInfo image)
+        {
+            var tag = GetImageCacheTag(item, image);
+            if (!string.IsNullOrEmpty(image.BlurHash))
+            {
+                if (dto.ImageBlurHashes == null)
+                {
+                    dto.ImageBlurHashes = new Dictionary<ImageType, Dictionary<string, string>>();
+                }
+
+                if (!dto.ImageBlurHashes.ContainsKey(image.Type))
+                {
+                    dto.ImageBlurHashes[image.Type] = new Dictionary<string, string>();
+                }
+
+                dto.ImageBlurHashes[image.Type][tag] = image.BlurHash;
+            }
+
+            return tag;
+        }
+
+        private string[] GetTagsAndFillBlurhashes(BaseItemDto dto, BaseItem item, ImageType imageType, int limit)
+        {
+            return GetTagsAndFillBlurhashes(dto, item, imageType, item.GetImages(imageType).Take(limit).ToList());
+        }
+
+        private string[] GetTagsAndFillBlurhashes(BaseItemDto dto, BaseItem item, ImageType imageType, List<ItemImageInfo> images)
+        {
+            var tags = GetImageTags(item, images);
+            var hashes = new Dictionary<string, string>();
+            for (int i = 0; i < images.Count; i++)
+            {
+                var img = images[i];
+                if (!string.IsNullOrEmpty(img.BlurHash))
+                {
+                    var tag = tags[i];
+                    hashes[tag] = img.BlurHash;
+                }
+            }
+
+            if (hashes.Count > 0)
+            {
+                if (dto.ImageBlurHashes == null)
+                {
+                    dto.ImageBlurHashes = new Dictionary<ImageType, Dictionary<string, string>>();
+                }
+
+                dto.ImageBlurHashes[imageType] = hashes;
+            }
+
+            return tags;
+        }
+
         /// <summary>
         /// Sets simple property values on a DTOBaseItem
         /// </summary>
@@ -674,8 +738,8 @@ namespace Emby.Server.Implementations.Dto
                 dto.LockData = item.IsLocked;
                 dto.ForcedSortName = item.ForcedSortName;
             }
-            dto.Container = item.Container;
 
+            dto.Container = item.Container;
             dto.EndDate = item.EndDate;
 
             if (options.ContainsField(ItemFields.ExternalUrls))
@@ -694,10 +758,12 @@ namespace Emby.Server.Implementations.Dto
                 dto.AspectRatio = hasAspectRatio.AspectRatio;
             }
 
+            dto.ImageBlurHashes = new Dictionary<ImageType, Dictionary<string, string>>();
+
             var backdropLimit = options.GetImageLimit(ImageType.Backdrop);
             if (backdropLimit > 0)
             {
-                dto.BackdropImageTags = GetImageTags(item, item.GetImages(ImageType.Backdrop).Take(backdropLimit).ToList());
+                dto.BackdropImageTags = GetTagsAndFillBlurhashes(dto, item, ImageType.Backdrop, backdropLimit);
             }
 
             if (options.ContainsField(ItemFields.ScreenshotImageTags))
@@ -705,7 +771,7 @@ namespace Emby.Server.Implementations.Dto
                 var screenshotLimit = options.GetImageLimit(ImageType.Screenshot);
                 if (screenshotLimit > 0)
                 {
-                    dto.ScreenshotImageTags = GetImageTags(item, item.GetImages(ImageType.Screenshot).Take(screenshotLimit).ToList());
+                    dto.ScreenshotImageTags = GetTagsAndFillBlurhashes(dto, item, ImageType.Screenshot, screenshotLimit);
                 }
             }
 
@@ -721,12 +787,11 @@ namespace Emby.Server.Implementations.Dto
 
                 // Prevent implicitly captured closure
                 var currentItem = item;
-                foreach (var image in currentItem.ImageInfos.Where(i => !currentItem.AllowsMultipleImages(i.Type))
+                foreach (var image in currentItem.ImageInfos.Where(i => !currentItem.AllowsMultipleImages(i.Type)))
-                    .ToList())
                 {
                     if (options.GetImageLimit(image.Type) > 0)
                     {
-                        var tag = GetImageCacheTag(item, image);
+                        var tag = GetTagAndFillBlurhash(dto, item, image);
 
                         if (tag != null)
                         {
@@ -871,8 +936,7 @@ namespace Emby.Server.Implementations.Dto
                 if (albumParent != null)
                 {
                     dto.AlbumId = albumParent.Id;
-
+                    dto.AlbumPrimaryImageTag = GetTagAndFillBlurhash(dto, albumParent, ImageType.Primary);
-                    dto.AlbumPrimaryImageTag = GetImageCacheTag(albumParent, ImageType.Primary);
                 }
 
                 //if (options.ContainsField(ItemFields.MediaSourceCount))
@@ -1099,7 +1163,7 @@ namespace Emby.Server.Implementations.Dto
                     episodeSeries = episodeSeries ?? episode.Series;
                     if (episodeSeries != null)
                     {
-                        dto.SeriesPrimaryImageTag = GetImageCacheTag(episodeSeries, ImageType.Primary);
+                        dto.SeriesPrimaryImageTag = GetTagAndFillBlurhash(dto, episodeSeries, ImageType.Primary);
                     }
                 }
 
@@ -1145,7 +1209,7 @@ namespace Emby.Server.Implementations.Dto
                     series = series ?? season.Series;
                     if (series != null)
                     {
-                        dto.SeriesPrimaryImageTag = GetImageCacheTag(series, ImageType.Primary);
+                        dto.SeriesPrimaryImageTag = GetTagAndFillBlurhash(dto, series, ImageType.Primary);
                     }
                 }
             }
@@ -1275,7 +1339,7 @@ namespace Emby.Server.Implementations.Dto
                     if (image != null)
                     {
                         dto.ParentLogoItemId = GetDtoId(parent);
-                        dto.ParentLogoImageTag = GetImageCacheTag(parent, image);
+                        dto.ParentLogoImageTag = GetTagAndFillBlurhash(dto, parent, image);
                     }
                 }
                 if (artLimit > 0 && !(imageTags != null && imageTags.ContainsKey(ImageType.Art)) && dto.ParentArtItemId == null)
@@ -1285,7 +1349,7 @@ namespace Emby.Server.Implementations.Dto
                     if (image != null)
                     {
                         dto.ParentArtItemId = GetDtoId(parent);
-                        dto.ParentArtImageTag = GetImageCacheTag(parent, image);
+                        dto.ParentArtImageTag = GetTagAndFillBlurhash(dto, parent, image);
                     }
                 }
                 if (thumbLimit > 0 && !(imageTags != null && imageTags.ContainsKey(ImageType.Thumb)) && (dto.ParentThumbItemId == null || parent is Series) && !(parent is ICollectionFolder) && !(parent is UserView))
@@ -1295,7 +1359,7 @@ namespace Emby.Server.Implementations.Dto
                     if (image != null)
                     {
                         dto.ParentThumbItemId = GetDtoId(parent);
-                        dto.ParentThumbImageTag = GetImageCacheTag(parent, image);
+                        dto.ParentThumbImageTag = GetTagAndFillBlurhash(dto, parent, image);
                     }
                 }
                 if (backdropLimit > 0 && !((dto.BackdropImageTags != null && dto.BackdropImageTags.Length > 0) || (dto.ParentBackdropImageTags != null && dto.ParentBackdropImageTags.Length > 0)))
@@ -1305,7 +1369,7 @@ namespace Emby.Server.Implementations.Dto
                     if (images.Count > 0)
                     {
                         dto.ParentBackdropItemId = GetDtoId(parent);
-                        dto.ParentBackdropImageTags = GetImageTags(parent, images);
+                        dto.ParentBackdropImageTags = GetTagsAndFillBlurhashes(dto, parent, ImageType.Backdrop, images);
                     }
                 }
 

Emby.Server.Implementations/Library/LibraryManager.cs

@@ -21,6 +21,7 @@ using MediaBrowser.Common.Extensions;
 using MediaBrowser.Common.Progress;
 using MediaBrowser.Controller;
 using MediaBrowser.Controller.Configuration;
+using MediaBrowser.Controller.Drawing;
 using MediaBrowser.Controller.Dto;
 using MediaBrowser.Controller.Entities;
 using MediaBrowser.Controller.Entities.Audio;
@@ -35,6 +36,7 @@ using MediaBrowser.Controller.Resolvers;
 using MediaBrowser.Controller.Sorting;
 using MediaBrowser.Model.Configuration;
 using MediaBrowser.Model.Dlna;
+using MediaBrowser.Model.Drawing;
 using MediaBrowser.Model.Dto;
 using MediaBrowser.Model.Entities;
 using MediaBrowser.Model.IO;
@@ -67,6 +69,7 @@ namespace Emby.Server.Implementations.Library
         private readonly IFileSystem _fileSystem;
         private readonly IItemRepository _itemRepository;
         private readonly ConcurrentDictionary<Guid, BaseItem> _libraryItemsCache;
+        private readonly IImageProcessor _imageProcessor;
 
         private NamingOptions _namingOptions;
         private string[] _videoFileExtensions;
@@ -147,7 +150,8 @@ namespace Emby.Server.Implementations.Library
             Lazy<IProviderManager> providerManagerFactory,
             Lazy<IUserViewManager> userviewManagerFactory,
             IMediaEncoder mediaEncoder,
-            IItemRepository itemRepository)
+            IItemRepository itemRepository,
+            IImageProcessor imageProcessor)
         {
             _appHost = appHost;
             _logger = logger;
@@ -161,6 +165,7 @@ namespace Emby.Server.Implementations.Library
             _userviewManagerFactory = userviewManagerFactory;
             _mediaEncoder = mediaEncoder;
             _itemRepository = itemRepository;
+            _imageProcessor = imageProcessor;
 
             _libraryItemsCache = new ConcurrentDictionary<Guid, BaseItem>();
 
@@ -1815,10 +1820,90 @@ namespace Emby.Server.Implementations.Library
             }
         }
 
-        public void UpdateImages(BaseItem item)
+        private bool ImageNeedsRefresh(ItemImageInfo image)
         {
-            _itemRepository.SaveImages(item);
+            if (image.Path != null && image.IsLocalFile)
+            {
+                if (image.Width == 0 || image.Height == 0 || string.IsNullOrEmpty(image.BlurHash))
+                {
+                    return true;
+                }
 
+                try
+                {
+                    return _fileSystem.GetLastWriteTimeUtc(image.Path) != image.DateModified;
+                }
+                catch (Exception ex)
+                {
+                    _logger.LogError(ex, "Cannot get file info for {0}", image.Path);
+                    return false;
+                }
+            }
+
+            return image.Path != null && !image.IsLocalFile;
+        }
+
+        public void UpdateImages(BaseItem item, bool forceUpdate = false)
+        {
+            if (item == null)
+            {
+                throw new ArgumentNullException(nameof(item));
+            }
+
+            var outdated = forceUpdate ? item.ImageInfos.Where(i => i.Path != null).ToArray() : item.ImageInfos.Where(ImageNeedsRefresh).ToArray();
+            if (outdated.Length == 0)
+            {
+                RegisterItem(item);
+                return;
+            }
+
+            foreach (var img in outdated)
+            {
+                var image = img;
+                if (!img.IsLocalFile)
+                {
+                    try
+                    {
+                        var index = item.GetImageIndex(img);
+                        image = ConvertImageToLocal(item, img, index).ConfigureAwait(false).GetAwaiter().GetResult();
+                    }
+                    catch (ArgumentException)
+                    {
+                        _logger.LogWarning("Cannot get image index for {0}", img.Path);
+                        continue;
+                    }
+                    catch (InvalidOperationException)
+                    {
+                        _logger.LogWarning("Cannot fetch image from {0}", img.Path);
+                        continue;
+                    }
+                }
+
+                ImageDimensions size = _imageProcessor.GetImageDimensions(item, image);
+                image.Width = size.Width;
+                image.Height = size.Height;
+
+                try
+                {
+                    image.BlurHash = _imageProcessor.GetImageBlurHash(image.Path);
+                }
+                catch (Exception ex)
+                {
+                    _logger.LogError(ex, "Cannot compute blurhash for {0}", image.Path);
+                    image.BlurHash = string.Empty;
+                }
+
+                try
+                {
+                    image.DateModified = _fileSystem.GetLastWriteTimeUtc(image.Path);
+                }
+                catch (Exception ex)
+                {
+                    _logger.LogError(ex, "Cannot update DateModified for {0}", image.Path);
+                }
+            }
+
+            _itemRepository.SaveImages(item);
             RegisterItem(item);
         }
 
@@ -1839,7 +1924,7 @@ namespace Emby.Server.Implementations.Library
 
                 item.DateLastSaved = DateTime.UtcNow;
 
-                RegisterItem(item);
+                UpdateImages(item, updateReason >= ItemUpdateType.ImageUpdate);
             }
 
             _itemRepository.SaveItems(itemsList, cancellationToken);

Jellyfin.Drawing.Skia/Jellyfin.Drawing.Skia.csproj

@@ -18,6 +18,8 @@
   </ItemGroup>
 
   <ItemGroup>
+    <PackageReference Include="BlurHashSharp" Version="1.0.1" />
+    <PackageReference Include="BlurHashSharp.SkiaSharp" Version="1.0.0" />
     <PackageReference Include="SkiaSharp" Version="1.68.1" />
     <PackageReference Include="SkiaSharp.NativeAssets.Linux" Version="1.68.1" />
     <PackageReference Include="Jellyfin.SkiaSharp.NativeAssets.LinuxArm" Version="1.68.1" />

Jellyfin.Drawing.Skia/SkiaEncoder.cs

@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Globalization;
 using System.IO;
+using BlurHashSharp.SkiaSharp;
 using MediaBrowser.Common.Configuration;
 using MediaBrowser.Controller.Drawing;
 using MediaBrowser.Controller.Extensions;
@@ -229,6 +230,20 @@ namespace Jellyfin.Drawing.Skia
             }
         }
 
+        /// <inheritdoc />
+        /// <exception cref="ArgumentNullException">The path is null.</exception>
+        /// <exception cref="FileNotFoundException">The path is not valid.</exception>
+        /// <exception cref="SkiaCodecException">The file at the specified path could not be used to generate a codec.</exception>
+        public string GetImageBlurHash(int xComp, int yComp, string path)
+        {
+            if (path == null)
+            {
+                throw new ArgumentNullException(nameof(path));
+            }
+
+            return BlurHashEncoder.Encode(xComp, yComp, path);
+        }
+
         private static bool HasDiacritics(string text)
             => !string.Equals(text, text.RemoveDiacritics(), StringComparison.Ordinal);
 

MediaBrowser.Api/Images/ImageService.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Globalization;
 using System.IO;
 using System.Linq;
+using System.Runtime.CompilerServices;
 using System.Threading;
 using System.Threading.Tasks;
 using MediaBrowser.Common.Extensions;
@@ -280,9 +281,16 @@ namespace MediaBrowser.Api.Images
         public List<ImageInfo> GetItemImageInfos(BaseItem item)
         {
             var list = new List<ImageInfo>();
-
             var itemImages = item.ImageInfos;
 
+            if (itemImages.Length == 0)
+            {
+                // short-circuit
+                return list;
+            }
+
+            _libraryManager.UpdateImages(item); // this makes sure dimensions and hashes are correct
+
             foreach (var image in itemImages)
             {
                 if (!item.AllowsMultipleImages(image.Type))
@@ -323,6 +331,7 @@ namespace MediaBrowser.Api.Images
         {
             int? width = null;
             int? height = null;
+            string blurhash = null;
             long length = 0;
 
             try
@@ -332,10 +341,9 @@ namespace MediaBrowser.Api.Images
                     var fileInfo = _fileSystem.GetFileInfo(info.Path);
                     length = fileInfo.Length;
 
-                    ImageDimensions size = _imageProcessor.GetImageDimensions(item, info);
+                    blurhash = info.BlurHash;
-                    _libraryManager.UpdateImages(item);
+                    width = info.Width;
-                    width = size.Width;
+                    height = info.Height;
-                    height = size.Height;
 
                     if (width <= 0 || height <= 0)
                     {
@@ -358,6 +366,7 @@ namespace MediaBrowser.Api.Images
                     ImageType = info.Type,
                     ImageTag = _imageProcessor.GetImageCacheTag(item, info),
                     Size = length,
+                    BlurHash = blurhash,
                     Width = width,
                     Height = height
                 };

MediaBrowser.Controller/Drawing/IImageEncoder.cs

@@ -43,6 +43,15 @@ namespace MediaBrowser.Controller.Drawing
         /// <returns>The image dimensions.</returns>
         ImageDimensions GetImageSize(string path);
 
+        /// <summary>
+        /// Gets the blurhash of an image.
+        /// </summary>
+        /// <param name="xComp">Amount of X components of DCT to take.</param>
+        /// <param name="yComp">Amount of Y components of DCT to take.</param>
+        /// <param name="path">The filepath of the image.</param>
+        /// <returns>The blurhash.</returns>
+        string GetImageBlurHash(int xComp, int yComp, string path);
+
         /// <summary>
         /// Encode an image.
         /// </summary>

MediaBrowser.Controller/Drawing/IImageProcessor.cs

@@ -40,6 +40,13 @@ namespace MediaBrowser.Controller.Drawing
         /// <returns>ImageDimensions</returns>
         ImageDimensions GetImageDimensions(BaseItem item, ItemImageInfo info);
 
+        /// <summary>
+        /// Gets the blurhash of the image.
+        /// </summary>
+        /// <param name="path">Path to the image file.</param>
+        /// <returns>BlurHash</returns>
+        string GetImageBlurHash(string path);
+
         /// <summary>
         /// Gets the image cache tag.
         /// </summary>
@@ -47,6 +54,7 @@ namespace MediaBrowser.Controller.Drawing
         /// <param name="image">The image.</param>
         /// <returns>Guid.</returns>
         string GetImageCacheTag(BaseItem item, ItemImageInfo image);
+
         string GetImageCacheTag(BaseItem item, ChapterInfo info);
 
         /// <summary>

MediaBrowser.Controller/Entities/BaseItem.cs

@@ -1374,6 +1374,7 @@ namespace MediaBrowser.Controller.Entities
                         new List<FileSystemMetadata>();
 
                     var ownedItemsChanged = await RefreshedOwnedItems(options, files, cancellationToken).ConfigureAwait(false);
+                    LibraryManager.UpdateImages(this); // ensure all image properties in DB are fresh
 
                     if (ownedItemsChanged)
                     {
@@ -2222,6 +2223,7 @@ namespace MediaBrowser.Controller.Entities
                 existingImage.DateModified = image.DateModified;
                 existingImage.Width = image.Width;
                 existingImage.Height = image.Height;
+                existingImage.BlurHash = image.BlurHash;
             }
             else
             {
@@ -2373,6 +2375,46 @@ namespace MediaBrowser.Controller.Entities
                 .ElementAtOrDefault(imageIndex);
         }
 
+        /// <summary>
+        /// Computes image index for given image or raises if no matching image found.
+        /// </summary>
+        /// <param name="image">Image to compute index for.</param>
+        /// <exception cref="ArgumentException">Image index cannot be computed as no matching image found.
+        /// </exception>
+        /// <returns>Image index.</returns>
+        public int GetImageIndex(ItemImageInfo image)
+        {
+            if (image == null)
+            {
+                throw new ArgumentNullException(nameof(image));
+            }
+
+            if (image.Type == ImageType.Chapter)
+            {
+                var chapters = ItemRepository.GetChapters(this);
+                for (var i = 0; i < chapters.Count; i++)
+                {
+                    if (chapters[i].ImagePath == image.Path)
+                    {
+                        return i;
+                    }
+                }
+
+                throw new ArgumentException("No chapter index found for image path", image.Path);
+            }
+
+            var images = GetImages(image.Type).ToArray();
+            for (var i = 0; i < images.Length; i++)
+            {
+                if (images[i].Path == image.Path)
+                {
+                    return i;
+                }
+            }
+
+            throw new ArgumentException("No image index found for image path", image.Path);
+        }
+
         public IEnumerable<ItemImageInfo> GetImages(ImageType imageType)
         {
             if (imageType == ImageType.Chapter)

MediaBrowser.Controller/Entities/Folder.cs

@@ -341,6 +341,11 @@ namespace MediaBrowser.Controller.Entities
                         {
                             currentChild.UpdateToRepository(ItemUpdateType.MetadataImport, cancellationToken);
                         }
+                        else
+                        {
+                            // metadata is up-to-date; make sure DB has correct images dimensions and hash
+                            LibraryManager.UpdateImages(currentChild);
+                        }
 
                         continue;
                     }

MediaBrowser.Controller/Entities/ItemImageInfo.cs

@@ -28,6 +28,12 @@ namespace MediaBrowser.Controller.Entities
 
         public int Height { get; set; }
 
+        /// <summary>
+        /// Gets or sets the blurhash.
+        /// </summary>
+        /// <value>The blurhash.</value>
+        public string BlurHash { get; set; }
+
         [JsonIgnore]
         public bool IsLocalFile => Path == null || !Path.StartsWith("http", StringComparison.OrdinalIgnoreCase);
     }

MediaBrowser.Controller/Library/ILibraryManager.cs

@@ -118,7 +118,7 @@ namespace MediaBrowser.Controller.Library
         /// </summary>
         void QueueLibraryScan();
 
-        void UpdateImages(BaseItem item);
+        void UpdateImages(BaseItem item, bool forceUpdate = false);
 
         /// <summary>
         /// Gets the default view.
@@ -195,6 +195,7 @@ namespace MediaBrowser.Controller.Library
         /// Updates the item.
         /// </summary>
         void UpdateItems(IEnumerable<BaseItem> items, BaseItem parent, ItemUpdateType updateReason, CancellationToken cancellationToken);
+
         void UpdateItem(BaseItem item, BaseItem parent, ItemUpdateType updateReason, CancellationToken cancellationToken);
 
         /// <summary>

MediaBrowser.Model/Dto/BaseItemDto.cs

@@ -510,6 +510,13 @@ namespace MediaBrowser.Model.Dto
         /// <value>The series thumb image tag.</value>
         public string SeriesThumbImageTag { get; set; }
 
+        /// <summary>
+        /// Gets or sets the blurhashes for the image tags.
+        /// Maps image type to dictionary mapping image tag to blurhash value.
+        /// </summary>
+        /// <value>The blurhashes.</value>
+        public Dictionary<ImageType, Dictionary<string, string>> ImageBlurHashes { get; set; }
+
         /// <summary>
         /// Gets or sets the series studio.
         /// </summary>

MediaBrowser.Model/Dto/ImageInfo.cs

@@ -30,6 +30,12 @@ namespace MediaBrowser.Model.Dto
         /// <value>The path.</value>
         public string Path { get; set; }
 
+        /// <summary>
+        /// Gets or sets the blurhash.
+        /// </summary>
+        /// <value>The blurhash.</value>
+        public string BlurHash { get; set; }
+
         /// <summary>
         /// Gets or sets the height.
         /// </summary>