Experimental resampler. Need y-axis fix

Former-commit-id: 9c4e407244d5f3c4dca2acfdae80d4a1b09e91e2
Former-commit-id: df3578fe9a9da69ec0306cddc3427dd706dec866
Former-commit-id: 2142bb6dd2a6a2b959093598792335443f853651

src/ImageProcessor/ImageProcessor.csproj

@@ -196,6 +196,7 @@
     <Compile Include="Samplers\Resamplers\BicubicResampler.cs" />
     <Compile Include="Samplers\ImageSampleExtensions.cs" />
     <Compile Include="Samplers\Resamplers\IResampler.cs" />
+    <Compile Include="Samplers\Resize - Copy.cs" />
     <Compile Include="Samplers\Resize.cs" />
   </ItemGroup>
   <ItemGroup>

src/ImageProcessor/Samplers/Resize - Copy.cs

@@ -0,0 +1,180 @@
+// <copyright file="Resize.cs" company="James South">
+// Copyright © James South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageProcessor.Samplers
+{
+    using System;
+    using System.Collections.Generic;
+
+    /// <summary>
+    /// Provides methods that allow the resizing of images using various resampling algorithms.
+    /// </summary>
+    public class Resize : ParallelImageProcessor
+    {
+        /// <summary>
+        /// The epsilon for comparing floating point numbers.
+        /// </summary>
+        private const float Epsilon = 0.0001f;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Resize"/> class.
+        /// </summary>
+        /// <param name="sampler">
+        /// The sampler to perform the resize operation.
+        /// </param>
+        public Resize(IResampler sampler)
+        {
+            Guard.NotNull(sampler, nameof(sampler));
+
+            this.Sampler = sampler;
+        }
+
+        /// <summary>
+        /// Gets the sampler to perform the resize operation.
+        /// </summary>
+        public IResampler Sampler { get; }
+
+        /// <inheritdoc/>
+        protected override void Apply(ImageBase target, ImageBase source, Rectangle targetRectangle, Rectangle sourceRectangle, int startY, int endY)
+        {
+            int sourceWidth = source.Width;
+            int sourceHeight = source.Height;
+
+            int width = target.Width;
+            int height = target.Height;
+
+            int targetY = targetRectangle.Y;
+            int startX = targetRectangle.X;
+            int endX = targetRectangle.Right;
+
+            // Scaling factors
+            double widthFactor = sourceWidth / (double)targetRectangle.Width;
+            double heightFactor = sourceHeight / (double)targetRectangle.Height;
+            int sectionHeight = endY - startY;
+
+            Weights[] horizontalWeights = this.PrecomputeWeights(targetRectangle.Width, sourceRectangle.Width, this.Sampler);
+            Weights[] verticalWeights = this.PrecomputeWeights(sectionHeight, (int)((sectionHeight * heightFactor) + .5), this.Sampler);
+
+            // Width and height decreased by 1
+            int maxHeight = sourceHeight - 1;
+            int maxWidth = sourceWidth - 1;
+
+            for (int y = startY; y < endY; y++)
+            {
+                List<Weight> verticalValues = verticalWeights[y - startY].Values;
+                double verticalSum = verticalWeights[y - startY].Sum;
+
+                for (int x = startX; x < endX; x++)
+                {
+                    List<Weight> horizontalValues = horizontalWeights[x - startX].Values;
+                    double horizontalSum = horizontalWeights[x - startX].Sum;
+
+
+                    // Destination color components
+                    double r = 0;
+                    double g = 0;
+                    double b = 0;
+                    double a = 0;
+
+                    foreach (Weight yw in verticalValues)
+                    {
+                        int originY = yw.Index + startY; //- targetY;//(int)(((y - targetY) * heightFactor) - 0.5);
+                        originY = originY.Clamp(0, maxHeight);
+
+                        foreach (Weight xw in horizontalValues)
+                        {
+                            int originX = xw.Index;//(int)(((x - startX) * widthFactor) - 0.5);
+                            originX = originX.Clamp(0, maxWidth);
+
+                            Bgra sourceColor = source[originX, originY];
+                            r += sourceColor.R * (yw.Value / verticalSum) * (xw.Value / horizontalSum);
+                            g += sourceColor.G * (yw.Value / verticalSum) * (xw.Value / horizontalSum);
+                            b += sourceColor.B * (yw.Value / verticalSum) * (xw.Value / horizontalSum);
+                            a += sourceColor.A * (yw.Value / verticalSum) * (xw.Value / horizontalSum);
+                        }
+                    }
+
+                    Bgra destinationColor = new Bgra(b.ToByte(), g.ToByte(), r.ToByte(), a.ToByte());
+                    target[x, y] = destinationColor;
+                }
+            }
+        }
+
+        private Weights[] PrecomputeWeights(int dstSize, int srcSize, IResampler sampler)
+        {
+            float du = srcSize / (float)dstSize;
+            float scale = du;
+
+            if (scale < 1)
+            {
+                scale = 1;
+            }
+
+            double ru = Math.Ceiling(scale * sampler.Radius);
+            Weights[] result = new Weights[dstSize];
+
+            for (int i = 0; i < dstSize; i++)
+            {
+                double fu = ((i + .5) * du) - 0.5;
+                int startU = (int)Math.Ceiling(fu - ru);
+
+                if (startU < 0)
+                {
+                    startU = 0;
+                }
+
+                int endU = (int)Math.Floor(fu + ru);
+
+                if (endU > srcSize - 1)
+                {
+                    endU = srcSize - 1;
+                }
+
+                double sum = 0;
+                result[i] = new Weights();
+
+                for (int a = startU; a <= endU; a++)
+                {
+                    double w = 255 * sampler.GetValue((a - fu) / scale);
+
+                    if (Math.Abs(w) > Epsilon)
+                    {
+                        sum += w;
+                        result[i].Values.Add(new Weight(a, w));
+                    }
+                }
+
+                result[i].Sum = sum;
+            }
+
+            return result;
+        }
+
+        public struct Weight
+        {
+            public Weight(int index, double value)
+            {
+                this.Index = index;
+                this.Value = value;
+            }
+
+            public readonly int Index;
+
+            public readonly double Value;
+        }
+
+        public class Weights
+        {
+            public Weights()
+            {
+                this.Values = new List<Weight>();
+            }
+
+            public List<Weight> Values { get; set; }
+
+            public double Sum { get; set; }
+        }
+    }
+}

src/ImageProcessor/Samplers/Resize.cs

@@ -10,7 +10,7 @@ namespace ImageProcessor.Samplers
     /// <summary>
     /// Provides methods that allow the resizing of images using various resampling algorithms.
     /// </summary>
-    public class Resize : ParallelImageProcessor
+    public class ResizeB : ParallelImageProcessor
     {
         /// <summary>
         /// The epsilon for comparing floating point numbers.
@@ -23,7 +23,7 @@ namespace ImageProcessor.Samplers
         /// <param name="sampler">
         /// The sampler to perform the resize operation.
         /// </param>
-        public Resize(IResampler sampler)
+        public ResizeB(IResampler sampler)
         {
             Guard.NotNull(sampler, nameof(sampler));
 

tests/ImageProcessor.Tests/Processors/ProcessorTestBase.cs

@@ -19,8 +19,8 @@ namespace ImageProcessor.Tests
         /// </summary>
         public static readonly List<string> Files = new List<string>
         {
-            "../../TestImages/Formats/Jpg/Backdrop.jpg",
-            "../../TestImages/Formats/Jpg/Calliphora.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"

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

@@ -13,18 +13,18 @@ namespace ImageProcessor.Tests
         public static readonly TheoryData<string, IResampler> Samplers =
             new TheoryData<string, IResampler>
             {
-                { "Bicubic", new BicubicResampler() },
-                { "Bilinear", new TriangleResampler() },
+                //{ "Bicubic", new BicubicResampler() },
+                //{ "Bilinear", new TriangleResampler() },
                 { "NearestNeighbour", new BoxResampler() },
-                { "Lanczos3", new Lanczos3Resampler() },
+                //{ "Lanczos3", new Lanczos3Resampler() },
                 { "Lanczos8", new Lanczos8Resampler() },
-                { "MitchellNetravali", new MitchellNetravaliResampler() },
-                { "Hermite", new HermiteResampler() },
-                { "Spline", new SplineResampler() },
-                { "Robidoux", new RobidouxResampler() },
-                { "RobidouxSharp", new RobidouxSharpResampler() },
-                { "RobidouxSoft", new RobidouxSoftResampler() },
-                { "Welch", new WelchResampler() }
+                //{ "MitchellNetravali", new MitchellNetravaliResampler() },
+                //{ "Hermite", new HermiteResampler() },
+                //{ "Spline", new SplineResampler() },
+                //{ "Robidoux", new RobidouxResampler() },
+                //{ "RobidouxSharp", new RobidouxSharpResampler() },
+                //{ "RobidouxSoft", new RobidouxSoftResampler() },
+                //{ "Welch", new WelchResampler() }
             };
 
         [Theory]
@@ -45,7 +45,7 @@ namespace ImageProcessor.Tests
                     string filename = Path.GetFileNameWithoutExtension(file) + "-" + name + Path.GetExtension(file);
                     using (FileStream output = File.OpenWrite($"Resized/{filename}"))
                     {
-                        image.Resize(100, 100, sampler).Save(output);
+                        image.Resize(500, 500, sampler).Save(output);
                     }
 
                     Trace.WriteLine($"{name}: {watch.ElapsedMilliseconds}ms");