diff --git a/bi/core.js b/bi/core.js
index 14b93d785..87caeb511 100644
--- a/bi/core.js
+++ b/bi/core.js
@@ -17112,8 +17112,8 @@ $(function () {
                 return false;
             }
             var rgb = this.rgb2json(this.hex2rgb(hex));
-            var grayLevel = (rgb.r * 0.299 + rgb.g * 0.587 + rgb.b * 0.114);
-            if (grayLevel < 192) {
+            var grayLevel = Math.round(rgb.r * 0.299 + rgb.g * 0.587 + rgb.b * 0.114);
+            if (grayLevel < 140) {
                 return true;
             }
             return false;
diff --git a/dist/core.js b/dist/core.js
index ff5a7c5c5..2c41386b7 100644
--- a/dist/core.js
+++ b/dist/core.js
@@ -22736,8 +22736,8 @@ $(function () {
                 return false;
             }
             var rgb = this.rgb2json(this.hex2rgb(hex));
-            var grayLevel = (rgb.r * 0.299 + rgb.g * 0.587 + rgb.b * 0.114);
-            if (grayLevel < 192) {
+            var grayLevel = Math.round(rgb.r * 0.299 + rgb.g * 0.587 + rgb.b * 0.114);
+            if (grayLevel < 140) {
                 return true;
             }
             return false;
diff --git a/src/core/func/function.js b/src/core/func/function.js
index 9dc982554..8e2256a93 100644
--- a/src/core/func/function.js
+++ b/src/core/func/function.js
@@ -187,8 +187,8 @@ $(function () {
                 return false;
             }
             var rgb = this.rgb2json(this.hex2rgb(hex));
-            var grayLevel = (rgb.r * 0.299 + rgb.g * 0.587 + rgb.b * 0.114);
-            if (grayLevel < 192) {
+            var grayLevel = Math.round(rgb.r * 0.299 + rgb.g * 0.587 + rgb.b * 0.114);
+            if (grayLevel < 140) {
                 return true;
             }
             return false;