Remove duplicate clamping and normalize vector scaling.

src/ImageSharp/PixelFormats/PixelBlenders/DefaultPixelBlenders.Generated.tt

@@ -81,13 +81,14 @@ namespace SixLabors.ImageSharp.PixelFormats.PixelBlenders
                 public override TPixel Blend(TPixel background, TPixel source, float amount)
                 {
                     TPixel dest = default;
-                    dest.PackFromScaledVector4(PorterDuffFunctions.<#=blender_composer#>(background.ToScaledVector4(),source.ToScaledVector4(),amount.Clamp(0,1)));
+                    dest.PackFromScaledVector4(PorterDuffFunctions.<#=blender_composer#>(background.ToScaledVector4(), source.ToScaledVector4(), amount.Clamp(0, 1)));
                     return dest;                    
                 }
 
                 /// <inheritdoc />
                 protected override void BlendFunction(Span<Vector4> destination, ReadOnlySpan<Vector4> background, ReadOnlySpan<Vector4> source, float amount)                
                 {
+                    amount = amount.Clamp(0, 1);
                     for (int i = 0; i < destination.Length; i++)
                     {
                         destination[i] = PorterDuffFunctions.<#=blender_composer#>(background[i], source[i], amount);
@@ -99,7 +100,7 @@ namespace SixLabors.ImageSharp.PixelFormats.PixelBlenders
                 {
                     for (int i = 0; i < destination.Length; i++)
                     {
-                        destination[i] = PorterDuffFunctions.<#=blender_composer#>(background[i], source[i], amount[i]);
+                        destination[i] = PorterDuffFunctions.<#=blender_composer#>(background[i], source[i], amount[i].Clamp(0, 1));
                     }                    
                 }
             }

src/ImageSharp/PixelFormats/PixelBlenders/PorterDuffFunctions.Generated.tt

@@ -27,7 +27,7 @@ namespace SixLabors.ImageSharp.PixelFormats.PixelBlenders
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static Vector4 <#=blender#>Src(Vector4 backdrop, Vector4 source, float opacity)
         {
-            source.W *= opacity.Clamp(0,1);
+            source.W *= opacity;
 
             return source;
         }
@@ -35,7 +35,7 @@ namespace SixLabors.ImageSharp.PixelFormats.PixelBlenders
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static Vector4 <#=blender#>SrcAtop(Vector4 backdrop, Vector4 source, float opacity)
         {
-            source.W *= opacity.Clamp(0,1);
+            source.W *= opacity;
 
             return Atop(backdrop, source, <#=blender#>(backdrop, source));
         }
@@ -43,7 +43,7 @@ namespace SixLabors.ImageSharp.PixelFormats.PixelBlenders
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static Vector4 <#=blender#>SrcOver(Vector4 backdrop, Vector4 source, float opacity)
         {
-            source.W *= opacity.Clamp(0,1);
+            source.W *= opacity;
 
             return Over(backdrop, source, <#=blender#>(backdrop, source));
         }
@@ -51,7 +51,7 @@ namespace SixLabors.ImageSharp.PixelFormats.PixelBlenders
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static Vector4 <#=blender#>SrcIn(Vector4 backdrop, Vector4 source, float opacity)
         {
-            source.W *= opacity.Clamp(0,1);
+            source.W *= opacity;
 
             return In(backdrop, source, <#=blender#>(backdrop, source));
         }
@@ -59,7 +59,7 @@ namespace SixLabors.ImageSharp.PixelFormats.PixelBlenders
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static Vector4 <#=blender#>SrcOut(Vector4 backdrop, Vector4 source, float opacity)
         {
-            source.W *= opacity.Clamp(0,1);
+            source.W *= opacity;
 
             return Out(backdrop, source);
         }
@@ -73,7 +73,7 @@ namespace SixLabors.ImageSharp.PixelFormats.PixelBlenders
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static Vector4 <#=blender#>DestAtop(Vector4 backdrop, Vector4 source, float opacity)
         {
-            source.W *= opacity.Clamp(0,1);
+            source.W *= opacity;
 
             return Atop(source, backdrop, <#=blender#>(source, backdrop));
         }
@@ -81,7 +81,7 @@ namespace SixLabors.ImageSharp.PixelFormats.PixelBlenders
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static Vector4 <#=blender#>DestOver(Vector4 backdrop, Vector4 source, float opacity)
         {
-            source.W *= opacity.Clamp(0,1);
+            source.W *= opacity;
 
             return Over(source, backdrop, <#=blender#>(source, backdrop));
         }
@@ -89,7 +89,7 @@ namespace SixLabors.ImageSharp.PixelFormats.PixelBlenders
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static Vector4 <#=blender#>DestIn(Vector4 backdrop, Vector4 source, float opacity)
         {
-            source.W *= opacity.Clamp(0,1);
+            source.W *= opacity;
 
             return In(source, backdrop, <#=blender#>(source, backdrop));
         }
@@ -97,7 +97,7 @@ namespace SixLabors.ImageSharp.PixelFormats.PixelBlenders
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static Vector4 <#=blender#>DestOut(Vector4 backdrop, Vector4 source, float opacity)
         {
-            source.W *= opacity.Clamp(0,1);
+            source.W *= opacity;
 
             return Out(source, backdrop);
         }
@@ -105,7 +105,7 @@ namespace SixLabors.ImageSharp.PixelFormats.PixelBlenders
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static Vector4 <#=blender#>Xor(Vector4 backdrop, Vector4 source, float opacity)
         {
-            source.W *= opacity.Clamp(0,1);
+            source.W *= opacity;
 
             return Xor(backdrop, source);
         }   
@@ -113,7 +113,7 @@ namespace SixLabors.ImageSharp.PixelFormats.PixelBlenders
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static Vector4 <#=blender#>Clear(Vector4 backdrop, Vector4 source, float opacity)
         {
-            source.W *= opacity.Clamp(0,1);
+            source.W *= opacity;
 
             return Clear(backdrop, source);
         }
@@ -126,8 +126,9 @@ namespace SixLabors.ImageSharp.PixelFormats.PixelBlenders
         public static TPixel <#=blender#><#=composer#><TPixel>(TPixel backdrop, TPixel source, float opacity)
             where TPixel : struct, IPixel<TPixel>
         {
+            opacity = opacity.Clamp(0, 1);
             TPixel dest = default;
-            dest.PackFromVector4(<#=blender#><#=composer#>(backdrop.ToVector4(),source.ToVector4(),opacity));
+            dest.PackFromScaledVector4(<#=blender#><#=composer#>(backdrop.ToScaledVector4(), source.ToScaledVector4(), opacity));
             return dest;
         }
 

src/ImageSharp/PixelFormats/PixelBlender{TPixel}.cs

@@ -130,7 +130,7 @@ namespace SixLabors.ImageSharp.PixelFormats
                 PixelOperations<TPixel>.Instance.ToScaledVector4(background, backgroundSpan, destination.Length);
                 PixelOperations<TPixelSrc>.Instance.ToScaledVector4(source, sourceSpan, destination.Length);
 
-                this.BlendFunction(destinationSpan, backgroundSpan, sourceSpan, amount.Clamp(0, 1));
+                this.BlendFunction(destinationSpan, backgroundSpan, sourceSpan, amount);
 
                 PixelOperations<TPixel>.Instance.PackFromScaledVector4(destinationSpan, destination, destination.Length);
             }