diff --git a/hgdriver/hgdev/image_process.cpp b/hgdriver/hgdev/image_process.cpp
index 704ba69..ee424f6 100644
--- a/hgdriver/hgdev/image_process.cpp
+++ b/hgdriver/hgdev/image_process.cpp
@@ -1075,9 +1075,10 @@ namespace hg_imgproc
 
 			double 		threshold = 40;
 			int 		edge = 30;
+			int dis = img_conf_.discardblank_percent;
 			if (img_conf_.is_autodiscradblank_vince)
-				img_conf_.discardblank_percent *= 1.5;
-			CImageApplyDiscardBlank discardblank(threshold, edge, img_conf_.discardblank_percent);
+				dis *= 1.5;
+			CImageApplyDiscardBlank discardblank(threshold, edge, dis);
 
 			discardblank.apply(mats, mats.size());