Added: ability to skip unneeded chunks for optimization mode

src/ImageSharp/Formats/Png/IPngEncoderOptions.cs

@@ -57,5 +57,10 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// Gets a value indicating whether this instance should write an Adam7 interlaced image.
         /// </summary>
         PngInterlaceMode? InterlaceMethod { get; }
+
+        /// <summary>
+        /// Gets a value indicating whether this instance should skip certain chunks to decrease file size
+        /// </summary>
+        bool Optimized { get; }
     }
 }

src/ImageSharp/Formats/Png/PngEncoderCore.cs

@@ -155,10 +155,15 @@ namespace SixLabors.ImageSharp.Formats.Png
             this.WriteHeaderChunk(stream);
             this.WritePaletteChunk(stream, quantized);
             this.WriteTransparencyChunk(stream, pngMetadata);
-            this.WritePhysicalChunk(stream, metadata);
-            this.WriteGammaChunk(stream);
-            this.WriteExifChunk(stream, metadata);
-            this.WriteTextChunks(stream, pngMetadata);
+
+            if (!this.options.Optimized)
+            {
+                this.WritePhysicalChunk(stream, metadata);
+                this.WriteGammaChunk(stream);
+                this.WriteExifChunk(stream, metadata);
+                this.WriteTextChunks(stream, pngMetadata);
+            }
+
             this.WriteDataChunks(image.Frames.RootFrame, quantized, stream);
             this.WriteEndChunk(stream);
             stream.Flush();

src/ImageSharp/Formats/Png/PngEncoderOptions.cs

@@ -29,6 +29,7 @@ namespace SixLabors.ImageSharp.Formats.Png
             this.Quantizer = source.Quantizer;
             this.Threshold = source.Threshold;
             this.InterlaceMethod = source.InterlaceMethod;
+            this.Optimized = source.Optimized;
         }
 
         /// <summary>
@@ -78,5 +79,10 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// Gets or sets a value indicating whether this instance should write an Adam7 interlaced image.
         /// </summary>
         public PngInterlaceMode? InterlaceMethod { get; set; }
+
+        /// <summary>
+        /// Gets or sets a value indicating whether this instance should skip certain chunks to decrease file size
+        /// </summary>
+        public bool Optimized { get; set; }
     }
 }