From 4dd543ad7c712bdcc492c30fa476e023215a71c7 Mon Sep 17 00:00:00 2001
From: 13xforever <ilya.veselov@gmail.com>
Date: Tue, 27 Jan 2026 14:42:14 +0500
Subject: [PATCH] try all image orientations for tesseract ocr to improve
 results slightly

---
 Clients/GithubClient/GithubClient.csproj |  2 +-
 CompatBot/CompatBot.csproj               |  2 +-
 CompatBot/Ocr/Backend/Tesseract.cs       | 41 ++++++++++++++++++++++--
 3 files changed, 40 insertions(+), 5 deletions(-)

diff --git a/Clients/GithubClient/GithubClient.csproj b/Clients/GithubClient/GithubClient.csproj
index 154806aa..02444794 100644
--- a/Clients/GithubClient/GithubClient.csproj
+++ b/Clients/GithubClient/GithubClient.csproj
@@ -7,7 +7,7 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.Extensions.Caching.Memory" Version="10.0.2" />
     <PackageReference Include="Octokit" Version="14.0.0" />
-    <PackageReference Include="SharpCompress" Version="0.44.1" />
+    <PackageReference Include="SharpCompress" Version="0.44.4" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\CompatApiClient\CompatApiClient.csproj" />
diff --git a/CompatBot/CompatBot.csproj b/CompatBot/CompatBot.csproj
index 54402cdc..634d409c 100644
--- a/CompatBot/CompatBot.csproj
+++ b/CompatBot/CompatBot.csproj
@@ -72,7 +72,7 @@
     <PackageReference Include="NLog.Extensions.Logging" Version="6.1.0" />
     <PackageReference Include="NReco.Text.AhoCorasickDoubleArrayTrie" Version="1.1.1" />
     <PackageReference Include="Result.Net" Version="1.7.0" />
-    <PackageReference Include="SharpCompress" Version="0.44.1" />
+    <PackageReference Include="SharpCompress" Version="0.44.4" />
     <PackageReference Include="SixLabors.ImageSharp.Drawing" Version="2.1.7" />
     <PackageReference Include="TesseractCSharp" Version="1.0.5" />
   </ItemGroup>
diff --git a/CompatBot/Ocr/Backend/Tesseract.cs b/CompatBot/Ocr/Backend/Tesseract.cs
index d76af7ec..22b56d91 100644
--- a/CompatBot/Ocr/Backend/Tesseract.cs
+++ b/CompatBot/Ocr/Backend/Tesseract.cs
@@ -9,6 +9,7 @@ namespace CompatBot.Ocr.Backend;
 internal class Tesseract: BackendBase
 {
     private TesseractEngine engine;
+    private static readonly SemaphoreSlim limiter = new(1, 1);
 
     public override string Name => "tesseract";
 
@@ -68,9 +69,37 @@ internal class Tesseract: BackendBase
     public override async Task<(string result, double confidence)> GetTextAsync(string imgUrl, CancellationToken cancellationToken)
     {
         var imgData = await HttpClient.GetByteArrayAsync(imgUrl, cancellationToken).ConfigureAwait(false);
-        using var img = Pix.LoadFromMemory(imgData);
-        using var page = engine.Process(img);
-        return (page.GetText() ?? "", page.GetMeanConfidence());
+        var img = Pix.LoadFromMemory(imgData);
+        var result = new (string text, float confidence)[4];
+        await limiter.WaitAsync(Config.Cts.Token).ConfigureAwait(false);
+        try
+        {
+            var pass = 0;
+            do
+            {
+                using (var page = engine.Process(img))
+                    result[pass] = (page.GetText() ?? "", page.GetMeanConfidence());
+                if (pass < 3)
+                {
+                    var img2 = img.Rotate90((int)RotationDirection.Clockwise);
+                    img.Dispose();
+                    img = img2;
+                }
+                pass++;
+            } while (pass < 4);
+            var longestText = result
+                .Where(i => i.confidence > 0.5)
+                .OrderByDescending(i => i.text.Length)
+                .FirstOrDefault();
+            if (longestText is { confidence: > 0.5f, text.Length: > 0 })
+                return longestText;
+            else
+                return result.MaxBy(i => i.confidence);
+        }
+        finally
+        {
+            limiter.Release();
+        }
     }
 
     public override void Dispose()
@@ -78,4 +107,10 @@ internal class Tesseract: BackendBase
         base.Dispose();
         engine.Dispose();
     }
+
+    private enum RotationDirection
+    {
+        Clockwise = 1,
+        CounterClockwise = -1,
+    }
 }
\ No newline at end of file