Revert ref extensions.

src/ImageSharp/Common/Extensions/Vector4Extensions.cs

@@ -20,7 +20,7 @@ namespace SixLabors.ImageSharp
         /// <param name="source">The <see cref="Vector4"/> to premultiply</param>
         /// <returns>The <see cref="Vector4"/></returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static Vector4 Premultiply(this ref Vector4 source)
+        public static Vector4 Premultiply(this Vector4 source)
         {
             float w = source.W;
             Vector4 premultiplied = source * w;
@@ -29,12 +29,12 @@ namespace SixLabors.ImageSharp
         }
 
         /// <summary>
-        /// Reverses the result of premultiplying a vector via <see cref="Premultiply(ref Vector4)"/>.
+        /// Reverses the result of premultiplying a vector via <see cref="Premultiply(Vector4)"/>.
         /// </summary>
         /// <param name="source">The <see cref="Vector4"/> to premultiply</param>
         /// <returns>The <see cref="Vector4"/></returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static Vector4 UnPremultiply(this ref Vector4 source)
+        public static Vector4 UnPremultiply(this Vector4 source)
         {
             float w = source.W;
             Vector4 unpremultiplied = source / w;
@@ -50,10 +50,10 @@ namespace SixLabors.ImageSharp
         /// <param name="linear">The <see cref="Vector4"/> whose signal to compress.</param>
         /// <returns>The <see cref="Vector4"/>.</returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static Vector4 Compress(this ref Vector4 linear)
+        public static Vector4 Compress(this Vector4 linear)
         {
             // TODO: Is there a faster way to do this?
-            return new Vector4(Compress(ref linear.X), Compress(ref linear.Y), Compress(ref linear.Z), linear.W);
+            return new Vector4(Compress(linear.X), Compress(linear.Y), Compress(linear.Z), linear.W);
         }
 
         /// <summary>
@@ -64,10 +64,10 @@ namespace SixLabors.ImageSharp
         /// <param name="gamma">The <see cref="Rgba32"/> whose signal to expand.</param>
         /// <returns>The <see cref="Vector4"/>.</returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static Vector4 Expand(this ref Vector4 gamma)
+        public static Vector4 Expand(this Vector4 gamma)
         {
             // TODO: Is there a faster way to do this?
-            return new Vector4(Expand(ref gamma.X), Expand(ref gamma.Y), Expand(ref gamma.Z), gamma.W);
+            return new Vector4(Expand(gamma.X), Expand(gamma.Y), Expand(gamma.Z), gamma.W);
         }
 
         /// <summary>
@@ -80,7 +80,7 @@ namespace SixLabors.ImageSharp
         /// The <see cref="float"/>.
         /// </returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private static float Compress(ref float signal)
+        private static float Compress(float signal)
         {
             if (signal <= 0.0031308F)
             {
@@ -100,7 +100,7 @@ namespace SixLabors.ImageSharp
         /// The <see cref="float"/>.
         /// </returns>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private static float Expand(ref float signal)
+        private static float Expand(float signal)
         {
             if (signal <= 0.04045F)
             {

src/ImageSharp/Processing/Convolution/Processors/Convolution2DProcessor.cs

@@ -95,8 +95,7 @@ namespace SixLabors.ImageSharp.Processing.Convolution.Processors
                                     int offsetX = x + fxr;
 
                                     offsetX = offsetX.Clamp(0, maxX);
-                                    var currentColor = sourceOffsetRow[offsetX].ToVector4();
-                                    currentColor = currentColor.Premultiply();
+                                    Vector4 currentColor = sourceOffsetRow[offsetX].ToVector4().Premultiply();
 
                                     if (fy < kernelXHeight)
                                     {
@@ -121,8 +120,7 @@ namespace SixLabors.ImageSharp.Processing.Convolution.Processors
                             float blue = MathF.Sqrt((bX * bX) + (bY * bY));
 
                             ref TPixel pixel = ref targetRow[x];
-                            var result = new Vector4(red, green, blue, sourceRow[x].ToVector4().W);
-                            pixel.PackFromVector4(result.UnPremultiply());
+                            pixel.PackFromVector4(new Vector4(red, green, blue, sourceRow[x].ToVector4().W).UnPremultiply());
                         }
                     });
 

src/ImageSharp/Processing/Convolution/Processors/Convolution2PassProcessor.cs

@@ -110,8 +110,7 @@ namespace SixLabors.ImageSharp.Processing.Convolution.Processors
 
                                 offsetX = offsetX.Clamp(0, maxX);
 
-                                var currentColor = row[offsetX].ToVector4();
-                                currentColor = currentColor.Premultiply();
+                                Vector4 currentColor = row[offsetX].ToVector4().Premultiply();
                                 destination += kernel[fy, fx] * currentColor;
                             }
                         }

src/ImageSharp/Processing/Convolution/Processors/ConvolutionProcessor.cs

@@ -82,8 +82,7 @@ namespace SixLabors.ImageSharp.Processing.Convolution.Processors
 
                                  offsetX = offsetX.Clamp(0, maxX);
 
-                                 var currentColor = sourceOffsetRow[offsetX].ToVector4();
-                                 currentColor = currentColor.Premultiply();
+                                 Vector4 currentColor = sourceOffsetRow[offsetX].ToVector4().Premultiply();
                                  currentColor *= this.KernelXY[fy, fx];
 
                                  red += currentColor.X;
@@ -93,8 +92,7 @@ namespace SixLabors.ImageSharp.Processing.Convolution.Processors
                          }
 
                          ref TPixel pixel = ref targetRow[x];
-                         var result = new Vector4(red, green, blue, sourceRow[x].ToVector4().W);
-                         pixel.PackFromVector4(result.UnPremultiply());
+                         pixel.PackFromVector4(new Vector4(red, green, blue, sourceRow[x].ToVector4().W).UnPremultiply());
                      }
                  });
 

src/ImageSharp/Processing/Transforms/Processors/WeightsWindow.cs

@@ -96,7 +96,7 @@ namespace SixLabors.ImageSharp.Processing.Processors
 
         /// <summary>
         /// Computes the sum of vectors in 'rowSpan' weighted by weight values, pointed by this <see cref="WeightsWindow"/> instance.
-        /// Applies <see cref="Vector4Extensions.Expand(ref float)"/> to all input vectors.
+        /// Applies <see cref="Vector4Extensions.Expand(float)"/> to all input vectors.
         /// </summary>
         /// <param name="rowSpan">The input span of vectors</param>
         /// <param name="sourceX">The source row position.</param>
@@ -115,8 +115,7 @@ namespace SixLabors.ImageSharp.Processing.Processors
             {
                 float weight = Unsafe.Add(ref horizontalValues, i);
                 Vector4 v = Unsafe.Add(ref vecPtr, i);
-                v = v.Premultiply();
-                result += v.Expand() * weight;
+                result += v.Premultiply().Expand() * weight;
             }
 
             return result.UnPremultiply();