Implemented disposable pattern for spectral converter

src/ImageSharp/Formats/Jpeg/Components/Decoder/SpectralConverter{TPixel}.cs

@@ -13,15 +13,15 @@ using SixLabors.ImageSharp.PixelFormats;
 
 namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
 {
-    internal abstract class SpectralConverter
+    internal abstract class SpectralConverter : IDisposable
     {
         public abstract void InjectFrameData(JpegFrame frame, IRawJpegData jpegData);
 
         public abstract void ConvertStride();
+
+        public abstract void Dispose();
     }
 
-    // TODO: componentProcessors must be disposed!!!
-    // TODO: rgbaBuffer must be disposed!!!
     internal class SpectralConverter<TPixel> : SpectralConverter
         where TPixel : unmanaged, IPixel<TPixel>
     {
@@ -129,5 +129,15 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
 
             this.PixelRowCounter += this.PixelRowsPerStep;
         }
+
+        public override void Dispose()
+        {
+            foreach (JpegComponentPostProcessor cpp in this.componentProcessors)
+            {
+                cpp.Dispose();
+            }
+
+            this.rgbaBuffer.Dispose();
+        }
     }
 }

src/ImageSharp/Formats/Jpeg/JpegDecoderCore.cs

@@ -215,7 +215,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
         public Image<TPixel> Decode<TPixel>(BufferedReadStream stream, CancellationToken cancellationToken)
             where TPixel : unmanaged, IPixel<TPixel>
         {
-            var spectralConverter = new SpectralConverter<TPixel>(this.Configuration, cancellationToken);
+            using var spectralConverter = new SpectralConverter<TPixel>(this.Configuration, cancellationToken);
 
             this.scanDecoder = new HuffmanScanDecoder(stream, spectralConverter, cancellationToken);