Optimize Brightness

src/ImageSharp/Processing/Processors/Effects/BrightnessProcessor.cs

@@ -63,31 +63,26 @@ namespace ImageSharp.Processing.Processors
                 startY = 0;
             }
 
-            using (PixelAccessor<TPixel> sourcePixels = source.Lock())
-            {
             Parallel.For(
                 minY,
                 maxY,
                 this.ParallelOptions,
                 y =>
                     {
-                            int offsetY = y - startY;
+                        Span<TPixel> row = source.GetRowSpan(y - startY);
+
                         for (int x = minX; x < maxX; x++)
                         {
-                                int offsetX = x - startX;
+                            ref TPixel pixel = ref row[x - startX];
 
                             // TODO: Check this with other formats.
-                                Vector4 vector = sourcePixels[offsetX, offsetY].ToVector4().Expand();
+                            Vector4 vector = pixel.ToVector4().Expand();
                             Vector3 transformed = new Vector3(vector.X, vector.Y, vector.Z) + new Vector3(brightness);
                             vector = new Vector4(transformed, vector.W);
 
-                                TPixel packed = default(TPixel);
+                            pixel.PackFromVector4(vector.Compress());
-                                packed.PackFromVector4(vector.Compress());
-
-                                sourcePixels[offsetX, offsetY] = packed;
                         }
                     });
         }
     }
 }
-}