Merge pull request #396 from SixLabors/js/smart-encoder-options

Handle ICC profiles and default encoders

Author: JimBobSquarePants

samples/ImageSharp.Web.Sample/Pages/Index.cshtml

@@ -120,7 +120,29 @@
                 <img src="sixlabors.imagesharp.web.png" imagesharp-width="300" imagesharp-rsampler="Resampler.NearestNeighbor" />
             </p>
         </div>
+
     </section>
+    <hr />
+    <section>
+        <h2>ICC Profiles</h2>
+    <div>
+        <p>
+            <code>issue_2723.jpg?width=2000</code>
+        </p>
+        <p>
+            <img src="issue_2723.jpg" imagesharp-width="2000" />
+        </p>
+    </div>
+    <div>
+        <p>
+            <code>issue_2723.jpg?width=2000&format=webp</code>
+        </p>
+        <p>
+            <img src="issue_2723.jpg" imagesharp-width="2000" imagesharp-format="Format.WebP" />
+        </p>
+    </div>
+    </section>
+
     <hr />
     <section>
         <h2>Format</h2>

samples/ImageSharp.Web.Sample/wwwroot/issue_2723.jpg

@@ -344,8 +344,22 @@ private async Task ProcessRequestAsync(
 
                         await using (Stream inStream = await sourceImageResolver.OpenReadAsync())
                         {
-                            DecoderOptions decoderOptions = await this.options.OnBeforeLoadAsync.Invoke(imageCommandContext, this.options.Configuration)
-                                ?? new() { Configuration = this.options.Configuration };
+                            DecoderOptions decoderOptions =
+                                await this.options.OnBeforeLoadAsync.Invoke(imageCommandContext, this.options.Configuration)
+
+                                // If custom decoder options have not been provided and we know our options are the
+                                // default options it is safe to configure the decoder options to convert color profiles
+                                // since we know tha the JPEG encoder will always use YCbCr encoding instead of preserving the
+                                // original color encoding (potentially CMYK, Ycck) which can cause color loss.
+                                // Compaction is always safe as this simply removes sRGB color profile data from the image
+                                // metadata which is not required for correct processing.
+                                ?? new()
+                                {
+                                    Configuration = this.options.Configuration,
+                                    ColorProfileHandling = this.options.HasDefaultConfiguration
+                                    ? ColorProfileHandling.Convert
+                                    : ColorProfileHandling.Compact
+                                };
 
                             FormattedImage? image = null;
                             try

src/ImageSharp.Web/Middleware/ImageSharpMiddleware.cs

@@ -5,6 +5,9 @@
 using Microsoft.AspNetCore.Http;
 using Microsoft.IO;
 using SixLabors.ImageSharp.Formats;
+using SixLabors.ImageSharp.Formats.Jpeg;
+using SixLabors.ImageSharp.Formats.Png;
+using SixLabors.ImageSharp.Formats.Webp;
 using SixLabors.ImageSharp.Web.Commands;
 using SixLabors.ImageSharp.Web.Providers;
 
@@ -15,6 +18,8 @@ namespace SixLabors.ImageSharp.Web.Middleware;
 /// </summary>
 public class ImageSharpMiddlewareOptions
 {
+    private static readonly Configuration DefaultConfiguration = CreateDefaultConfiguration();
+
     private Func<ImageCommandContext, byte[], string> onComputeHMAC = (context, secret) =>
     {
         string uri = CaseHandlingUriBuilder.BuildRelative(
@@ -35,7 +40,12 @@ public class ImageSharpMiddlewareOptions
     /// <summary>
     /// Gets or sets the base library configuration.
     /// </summary>
-    public Configuration Configuration { get; set; } = Configuration.Default;
+    public Configuration Configuration { get; set; } = DefaultConfiguration;
+
+    /// <summary>
+    /// Gets a value indicating whether the current configuration is the default configuration.
+    /// </summary>
+    internal bool HasDefaultConfiguration => ReferenceEquals(this.Configuration, DefaultConfiguration);
 
     /// <summary>
     /// Gets or sets the recyclable memorystream manager used for managing pooled stream
@@ -176,4 +186,33 @@ public Func<HttpContext, Task> OnPrepareResponseAsync
             this.onPrepareResponseAsync = value;
         }
     }
+
+    private static Configuration CreateDefaultConfiguration()
+    {
+        // Build a Configuration for the requests that replaces the default JPEG, PNG, and WebP encoders
+        // with ones with compression options that are more suitable for web use.
+        // We do not skip metadata as that can affect things like orientation.
+        Configuration configuration = Configuration.Default.Clone();
+        configuration.ImageFormatsManager.SetEncoder(JpegFormat.Instance, new JpegEncoder()
+        {
+            Quality = 75,
+            Progressive = true,
+            Interleaved = true,
+            ColorType = JpegColorType.YCbCrRatio420,
+        });
+
+        configuration.ImageFormatsManager.SetEncoder(PngFormat.Instance, new PngEncoder()
+        {
+            CompressionLevel = PngCompressionLevel.BestCompression,
+            FilterMethod = PngFilterMethod.Adaptive,
+        });
+
+        configuration.ImageFormatsManager.SetEncoder(WebpFormat.Instance, new WebpEncoder()
+        {
+            Quality = 75,
+            Method = WebpEncodingMethod.BestQuality,
+        });
+
+        return configuration;
+    }
 }