More crop for VobSub

src/libse/Common/NikseBitmap.cs

@@ -914,6 +914,20 @@ namespace Nikse.SubtitleEdit.Core.Common
             return Height - y;
         }
 
+        public int CalcBottomTransparent()
+        {
+            var y = Height - 1;
+            for (; y > 0; y--)
+            {
+                if (!IsHorizontalLineTransparent(y))
+                {
+                    break;
+                }
+            }
+
+            return Height - y;
+        }
+
         public int CalcLeftCropping(Color color)
         {
             var x = 0;
@@ -968,6 +982,19 @@ namespace Nikse.SubtitleEdit.Core.Common
             return true;
         }
 
+        public bool IsHorizontalLineTransparent(int y)
+        {
+            for (var x = 0; x < Width; x++)
+            {
+                if (GetAlpha(x, y) > 1)
+                {
+                    return false;
+                }
+            }
+
+            return true;
+        }
+
         public void Fill(Color color)
         {
             var buffer = new byte[4];

src/ui/Forms/Ocr/VobSubOcr.cs

@@ -2330,9 +2330,11 @@ namespace Nikse.SubtitleEdit.Forms.Ocr
                 var nbmp = new NikseBitmap(bmp);
                 var topCropped = nbmp.CropTopTransparent(0);
                 top += topCropped;
+                var bottomCropped = nbmp.CalcBottomTransparent();
                 width = bmp.Width;
                 height = bmp.Height;
                 height -= topCropped;
+                height -= bottomCropped;
                 bmp.Dispose();
                 return;
             }