From c51bbc18e8150ec25218fcba40d91934f9386682 Mon Sep 17 00:00:00 2001
From: sinvo <admin@mcraft.cn>
Date: Thu, 19 Mar 2026 17:23:48 +0800
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Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 CamScanner.cs | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/CamScanner.cs b/CamScanner.cs
index a394535..122174e 100644
--- a/CamScanner.cs
+++ b/CamScanner.cs
@@ -367,20 +367,19 @@ public static class DocumentScanner
         Marshal.Copy(resultData, 0, normU8.Data, resultData.Length);
 
         // --- d: 非线性对比度增强（让文字更黑）---
-        // 除法归一化后文字大约在 180-240 范围，需要拉黑
         // 用 LUT 做分段映射：
-        //   0-200: 线性映射到 0-50（文字区域强力压暗）
-        //   200-255: 线性映射到 50-255（背景区域拉亮）
+        //   0-210: 线性映射到 0-30（文字区域强力压暗）
+        //   210-255: 线性映射到 30-255（背景区域拉亮）
         byte[] lut = new byte[256];
         for (int i = 0; i < 256; i++)
         {
-            if (i <= 200)
+            if (i <= 210)
             {
-                lut[i] = (byte)(i * 50 / 200);
+                lut[i] = (byte)(i * 30 / 210);
             }
             else
             {
-                lut[i] = (byte)(50 + (i - 200) * 205 / 55);
+                lut[i] = (byte)(30 + (i - 210) * 225 / 45);
             }
             if (lut[i] > 255) lut[i] = 255;
         }