diff --git a/CamScanner.cs b/CamScanner.cs
index f8ad70e..d99ab6a 100644
--- a/CamScanner.cs
+++ b/CamScanner.cs
@@ -437,8 +437,9 @@ public static class DocumentScanner
             }
         }
         int paperBright = (int)(centerSum / Math.Max(centerCount, 1));
-        int darkThresh = (int)(paperBright * 0.6);
-        int maxScanDepth = Math.Max(w, h) / 4; // 最多扫描1/4深度
+        int darkThresh = (int)(paperBright * 0.65);
+        int maxScanDepth = Math.Max(w, h) / 3; // 最多扫描1/3深度
+        int tolerance = 5; // 允许跳过最多5个亮像素继续扫描
 
         byte[] cleanedData = new byte[w * h];
         Marshal.Copy(cleaned.Data, cleanedData, 0, cleanedData.Length);
@@ -446,46 +447,86 @@ public static class DocumentScanner
         // 上边缘
         for (int x = 0; x < w; x++)
         {
+            int skipCount = 0;
+            int lastDark = -1;
             for (int y = 0; y < Math.Min(maxScanDepth, h); y++)
             {
                 if (grayData[y * w + x] < darkThresh)
-                    cleanedData[y * w + x] = 255;
+                {
+                    lastDark = y;
+                    skipCount = 0;
+                }
                 else
-                    break;
+                {
+                    skipCount++;
+                    if (skipCount > tolerance) break;
+                }
             }
+            for (int y = 0; y <= lastDark; y++)
+                cleanedData[y * w + x] = 255;
         }
         // 下边缘
         for (int x = 0; x < w; x++)
         {
+            int skipCount = 0;
+            int lastDark = h;
             for (int y = h - 1; y >= Math.Max(0, h - maxScanDepth); y--)
             {
                 if (grayData[y * w + x] < darkThresh)
-                    cleanedData[y * w + x] = 255;
+                {
+                    lastDark = y;
+                    skipCount = 0;
+                }
                 else
-                    break;
+                {
+                    skipCount++;
+                    if (skipCount > tolerance) break;
+                }
             }
+            for (int y = h - 1; y >= lastDark; y--)
+                cleanedData[y * w + x] = 255;
         }
         // 左边缘
         for (int py = 0; py < h; py++)
         {
+            int skipCount = 0;
+            int lastDark = -1;
             for (int x = 0; x < Math.Min(maxScanDepth, w); x++)
             {
                 if (grayData[py * w + x] < darkThresh)
-                    cleanedData[py * w + x] = 255;
+                {
+                    lastDark = x;
+                    skipCount = 0;
+                }
                 else
-                    break;
+                {
+                    skipCount++;
+                    if (skipCount > tolerance) break;
+                }
             }
+            for (int x = 0; x <= lastDark; x++)
+                cleanedData[py * w + x] = 255;
         }
         // 右边缘
         for (int py = 0; py < h; py++)
         {
+            int skipCount = 0;
+            int lastDark = w;
             for (int x = w - 1; x >= Math.Max(0, w - maxScanDepth); x--)
             {
                 if (grayData[py * w + x] < darkThresh)
-                    cleanedData[py * w + x] = 255;
+                {
+                    lastDark = x;
+                    skipCount = 0;
+                }
                 else
-                    break;
+                {
+                    skipCount++;
+                    if (skipCount > tolerance) break;
+                }
             }
+            for (int x = w - 1; x >= lastDark; x--)
+                cleanedData[py * w + x] = 255;
         }
         Marshal.Copy(cleanedData, 0, cleaned.Data, cleanedData.Length);