Polish 2 (#3555)

Co-authored-by: Robbie Davis <robbie@therobbiedavis.com>
Co-authored-by: Fesaa <77553571+Fesaa@users.noreply.github.com>

API/Extensions/ImageExtensions.cs

@@ -0,0 +1,122 @@
+using System;
+using System.IO;
+using NetVips;
+using SixLabors.ImageSharp;
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.ImageSharp.Processing;
+using Image = NetVips.Image;
+
+namespace API.Extensions;
+
+public static class ImageExtensions
+{
+    public static int GetResolution(this Image image)
+    {
+        return image.Width * image.Height;
+    }
+
+    /// <summary>
+    /// Smaller is better
+    /// </summary>
+    /// <param name="img1"></param>
+    /// <param name="img2"></param>
+    /// <returns></returns>
+    public static float GetMeanSquaredError(this Image<Rgba32> img1, Image<Rgba32> img2)
+    {
+        if (img1.Width != img2.Width || img1.Height != img2.Height)
+        {
+            img2.Mutate(x => x.Resize(img1.Width, img1.Height));
+        }
+
+        double totalDiff = 0;
+        for (var y = 0; y < img1.Height; y++)
+        {
+            for (var x = 0; x < img1.Width; x++)
+            {
+                var pixel1 = img1[x, y];
+                var pixel2 = img2[x, y];
+
+                var diff = Math.Pow(pixel1.R - pixel2.R, 2) +
+                           Math.Pow(pixel1.G - pixel2.G, 2) +
+                           Math.Pow(pixel1.B - pixel2.B, 2);
+                totalDiff += diff;
+            }
+        }
+
+        return (float)(totalDiff / (img1.Width * img1.Height));
+    }
+
+    public static float GetSimilarity(this string imagePath1, string imagePath2)
+    {
+        if (!File.Exists(imagePath1) || !File.Exists(imagePath2))
+        {
+            throw new FileNotFoundException("One or both image files do not exist");
+        }
+
+        // Calculate similarity score
+        return CalculateSimilarity(imagePath1, imagePath2);
+    }
+
+    /// <summary>
+    /// Determines which image is "better" based on similarity and resolution.
+    /// </summary>
+    /// <param name="imagePath1">Path to first image</param>
+    /// <param name="imagePath2">Path to second image</param>
+    /// <param name="similarityThreshold">Minimum similarity to consider images similar</param>
+    /// <returns>The path of the better image</returns>
+    public static string GetBetterImage(this string imagePath1, string imagePath2, float similarityThreshold = 0.7f)
+    {
+        if (!File.Exists(imagePath1) || !File.Exists(imagePath2))
+        {
+            throw new FileNotFoundException("One or both image files do not exist");
+        }
+
+        // Calculate similarity score
+        var similarity = CalculateSimilarity(imagePath1, imagePath2);
+
+        using var img1 = Image.NewFromFile(imagePath1, access: Enums.Access.Sequential);
+        using var img2 = Image.NewFromFile(imagePath2, access: Enums.Access.Sequential);
+
+        var resolution1 = img1.Width * img1.Height;
+        var resolution2 = img2.Width * img2.Height;
+
+        // If images are similar, choose the one with higher resolution
+        if (similarity >= similarityThreshold)
+        {
+            return resolution1 >= resolution2 ? imagePath1 : imagePath2;
+        }
+
+        // If images are not similar, allow the new image
+        return imagePath2;
+    }
+
+    /// <summary>
+    /// Calculate a similarity score (0-1f) based on resolution difference and MSE.
+    /// </summary>
+    /// <param name="imagePath1"></param>
+    /// <param name="imagePath2"></param>
+    /// <returns></returns>
+    private static float CalculateSimilarity(string imagePath1, string imagePath2)
+    {
+        if (!File.Exists(imagePath1) || !File.Exists(imagePath2))
+        {
+            return -1;
+        }
+
+        using var img1 = Image.NewFromFile(imagePath1, access: Enums.Access.Sequential);
+        using var img2 = Image.NewFromFile(imagePath2, access: Enums.Access.Sequential);
+
+        var res1 = img1.Width * img1.Height;
+        var res2 = img2.Width * img2.Height;
+        var resolutionDiff = Math.Abs(res1 - res2) / (float)Math.Max(res1, res2);
+
+        using var imgSharp1 = SixLabors.ImageSharp.Image.Load<Rgba32>(imagePath1);
+        using var imgSharp2 = SixLabors.ImageSharp.Image.Load<Rgba32>(imagePath2);
+
+        var mse = imgSharp1.GetMeanSquaredError(imgSharp2);
+        var normalizedMse = 1f - Math.Min(1f, mse / 65025f); // Normalize based on max color diff
+
+        // Final similarity score (weighted)
+        return Math.Max(0f, 1f - (resolutionDiff * 0.5f) - (1f - normalizedMse) * 0.5f);
+    }
+}