Add new test image for rewrite

Former-commit-id: 894501ba723e1643831c3917acb0bd7e064fc75b
Former-commit-id: a1bce60477ba5acdf54f4432bdb646bd95326f29
Former-commit-id: c539e6aeab3edf3ebde7658fece6972c321b7362

src/ImageProcessor/ImageProcessor.csproj

@@ -181,6 +181,7 @@
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="Numerics\Rectangle.cs" />
     <Compile Include="Numerics\Size.cs" />
+    <Compile Include="Samplers\Resamplers\Lanczos8Resampler.cs" />
     <Compile Include="Samplers\Resamplers\WelchResampler.cs" />
     <Compile Include="Samplers\Resamplers\CatmullRomResampler.cs" />
     <Compile Include="Samplers\Resamplers\RobidouxSoftResampler.cs" />

src/ImageProcessor/Samplers/Resamplers/Lanczos8Resampler.cs

@@ -0,0 +1,33 @@
+// <copyright file="Lanczos3Resampler.cs" company="James South">
+// Copyright © James South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageProcessor.Samplers
+{
+    /// <summary>
+    /// The function implements the Lanczos kernel algorithm as described on
+    /// <see href="https://en.wikipedia.org/wiki/Lanczos_resampling#Algorithm">Wikipedia</see>
+    /// </summary>
+    public class Lanczos8Resampler : IResampler
+    {
+        /// <inheritdoc/>
+        public double Radius => 8;
+
+        /// <inheritdoc/>
+        public double GetValue(double x)
+        {
+            if (x < 0)
+            {
+                x = -x;
+            }
+
+            if (x < 8)
+            {
+                return ImageMaths.SinC(x) * ImageMaths.SinC(x / 8f);
+            }
+
+            return 0;
+        }
+    }
+}

src/ImageProcessor/Samplers/Resize.cs

@@ -48,7 +48,7 @@ namespace ImageProcessor.Samplers
             int startX = targetRectangle.X;
             int endX = targetRectangle.Right;
             int right = (int)(this.Sampler.Radius + .5);
-            int left = -right;
+            int left = (-right) + 1;
 
             // Scaling factors
             double widthFactor = sourceWidth / (double)targetRectangle.Width;
@@ -86,7 +86,7 @@ namespace ImageProcessor.Samplers
                             for (int yy = left; yy <= right; yy++)
                             {
                                 // Get Y cooefficient
-                                double kernel1 = this.Sampler.GetValue(dy - yy);
+                                double kernel1 = this.Sampler.GetValue(yy - dy);
 
                                 if (Math.Abs(kernel1) < Epsilon)
                                 {
@@ -126,7 +126,7 @@ namespace ImageProcessor.Samplers
                                     }
 
                                     Bgra sourceColor = source[originX2, originY2];
-                                    sourceColor = PixelOperations.ToLinear(sourceColor);
+                                   // sourceColor = PixelOperations.ToLinear(sourceColor);
 
                                     r += kernel2 * sourceColor.R;
                                     g += kernel2 * sourceColor.G;
@@ -136,7 +136,7 @@ namespace ImageProcessor.Samplers
                             }
 
                             Bgra destinationColor = new Bgra(b.ToByte(), g.ToByte(), r.ToByte(), a.ToByte());
-                            destinationColor = PixelOperations.ToSrgb(destinationColor);
+                           // destinationColor = PixelOperations.ToSrgb(destinationColor);
                             target[x, y] = destinationColor;
                         }
                     }

tests/ImageProcessor.Tests/Processors/ProcessorTestBase.cs

@@ -19,11 +19,12 @@ namespace ImageProcessor.Tests
         /// </summary>
         public static readonly List<string> Files = new List<string>
         {
-            //"../../TestImages/Formats/Jpg/Backdrop.jpg",
+            "../../TestImages/Formats/Jpg/Backdrop.jpg",
             "../../TestImages/Formats/Jpg/Calliphora.jpg",
             //"../../TestImages/Formats/Bmp/Car.bmp",
             //"../../TestImages/Formats/Png/cmyk.png",
             //"../../TestImages/Formats/Gif/leaf.gif"
+            "../../TestImages/Formats/Gif/rings.gif"
 
             // { "../../TestImages/Formats/Gif/ani.gif" },
             // { "../../TestImages/Formats/Gif/ani2.gif" },

tests/ImageProcessor.Tests/Processors/Samplers/SamplerTests.cs

@@ -17,6 +17,7 @@ namespace ImageProcessor.Tests
                 { "Bilinear", new TriangleResampler() },
                 { "NearestNeighbour", new BoxResampler() },
                 { "Lanczos3", new Lanczos3Resampler() },
+                { "Lanczos8", new Lanczos8Resampler() },
                 { "MitchellNetravali", new MitchellNetravaliResampler() },
                 { "Hermite", new HermiteResampler() },
                 { "Spline", new SplineResampler() },
@@ -44,7 +45,7 @@ namespace ImageProcessor.Tests
                     string filename = Path.GetFileNameWithoutExtension(file) + "-" + name + Path.GetExtension(file);
                     using (FileStream output = File.OpenWrite($"Resized/{filename}"))
                     {
-                        image.Resize(200, 298, sampler).Save(output);
+                        image.Resize(100, 100, sampler).Save(output);
                     }
 
                     Trace.WriteLine($"{name}: {watch.ElapsedMilliseconds}ms");