test: resolve non-deterministic assertion in regional contrast saliency tests on Windows

Leiter.Tests/Algorithms/Saliency/SaliencyTests.cs

@@ -1,4 +1,3 @@
-
 using Xunit;
 using Leiter.Core;
 using Leiter.Pixels;
@@ -16,7 +15,7 @@ namespace Leiter.Tests.Algorithms.Saliency;
 public class SaliencyTests
 {
     /// <summary>
-    /// Verifies that the global contrast saliency should compute correctly behaves correctly.
+    /// Verifies that the global contrast saliency should compute correctly.
     /// </summary>
     [Fact]
     public void GlobalContrastSaliency_ShouldComputeCorrectly()
@@ -54,7 +53,33 @@ public void GlobalContrastSaliency_ShouldComputeCorrectly()
     }
 
     /// <summary>
-    /// Verifies that the regional contrast saliency should compute correctly behaves correctly.
+    /// Verifies that global contrast saliency of a contrasting object is correctly computed.
+    /// </summary>
+    [Fact]
+    public void GlobalContrastSaliency_ContrastingObject_ShouldBeMostSalient()
+    {
+        // 10x10 image with a 4x4 red square in the center (16 pixels, 16%) and black background
+        var img = new SequentialMatrix<Rgb8>(10, 10);
+        img.SetAll(new Rgb8(0, 0, 0));
+        for (int y = 3; y <= 6; y++)
+        {
+            for (int x = 3; x <= 6; x++)
+            {
+                img[x, y] = new Rgb8(255, 0, 0);
+            }
+        }
+
+        var saliency = GlobalContrastSaliency.ComputeSaliency(img, enableColorSpaceSmoothing: false);
+
+        // The contrasting red region should have highest saliency (1.0)
+        Assert.Equal(1.0, saliency[5, 5].Value, 4);
+
+        // The black background should have the lowest saliency (0.0)
+        Assert.Equal(0.0, saliency[0, 0].Value, 4);
+    }
+
+    /// <summary>
+    /// Verifies that the regional contrast saliency should compute correctly.
     /// </summary>
     [Fact]
     public void RegionalContrastSaliency_ShouldComputeCorrectly()
@@ -87,12 +112,42 @@ public void RegionalContrastSaliency_ShouldComputeCorrectly()
         Assert.Equal(0.0, minS, 4);
         Assert.Equal(1.0, maxS, 4);
 
-        // Verify regional saliency is not all flat zeros/ones and varies by region
-        Assert.True(saliency[0, 0].Value < saliency[10, 10].Value);
+        // Verify regional saliency contains various levels (i.e. not all flat zeros/ones)
+        Assert.True(saliency.Any(p => p.Value > 0.0 && p.Value < 1.0));
 
         // Turn off smoothing and border calculation to test the alternate branches
         var saliencyRaw = RegionalContrastSaliency.ComputeSaliency(img, segmentation, enableSmoothing: false, computeBorderRegions: false);
         Assert.Equal(20, saliencyRaw.Width);
         Assert.True(saliencyRaw.Min(p => p.Value) >= 0.0);
     }
+
+    /// <summary>
+    /// Verifies that regional contrast saliency of a contrasting object is correctly computed.
+    /// </summary>
+    [Fact]
+    public void RegionalContrastSaliency_ContrastingObject_ShouldBeMostSalient()
+    {
+        // 12x12 image with a 4x4 red square in the center (16 pixels) and black background
+        var img = new SequentialMatrix<Rgb8>(12, 12);
+        img.SetAll(new Rgb8(0, 0, 0));
+        for (int y = 4; y <= 7; y++)
+        {
+            for (int x = 4; x <= 7; x++)
+            {
+                img[x, y] = new Rgb8(255, 0, 0);
+            }
+        }
+
+        // Segment the image. With exact colors, the segment boundaries are completely clear.
+        var segmentation = EgbiSegmentation.Segment(img, kFactor: 1.0, epsilon: 1.0, minSegmentSize: 4);
+
+        // Compute regional saliency
+        var saliency = RegionalContrastSaliency.ComputeSaliency(img, segmentation, enableSmoothing: false, computeBorderRegions: false);
+
+        // The contrasting center red region should have highest saliency (1.0)
+        Assert.Equal(1.0, saliency[5, 5].Value, 4);
+
+        // The background black region should have the lowest saliency (0.0)
+        Assert.Equal(0.0, saliency[0, 0].Value, 4);
+    }
 }