diff --git a/README.md b/README.md
index d8ff800..3405dd4 100644
--- a/README.md
+++ b/README.md
@@ -56,7 +56,7 @@ MinGW-w64 (Use recommended) or other GCC
 ```
 #### For everything else:
 ```
-GCC
+GCC, libpng
     
 X11 with the XTest extension (also known as the Xtst library)
 
diff --git a/README_zh.md b/README_zh.md
index e4e64a1..b9800c0 100644
--- a/README_zh.md
+++ b/README_zh.md
@@ -54,7 +54,7 @@ MinGW-w64 (推荐使用) or other GCC
 ```
 #### For everything else (Linux 等其他系统):
 ```
-GCC
+GCC, libpng
     
 X11 with the XTest extension (also known as the Xtst library)
 
diff --git a/robotgo.go b/robotgo.go
index cc1022c..ab29081 100644
--- a/robotgo.go
+++ b/robotgo.go
@@ -850,10 +850,12 @@ func internalFindBitmap(bit, sbit C.MMBitmapRef, tolerance float64) (int, int) {
 	return int(pos.x), int(pos.y)
 }
 
-// FindBitmap find the bitmap
+// FindBitmap find the bitmap's pos
 //
 //	robotgo.FindBitmap(bitmap, subbitamp C.MMBitmapRef, tolerance float64)
 //
+//  |tolerance| should be in the range 0.0f - 1.0f, denoting how closely the
+//  colors in the bitmaps need to match, with 0 being exact and 1 being any.
 func FindBitmap(bit C.MMBitmapRef, args ...interface{}) (int, int) {
 	var (
 		sbit      C.MMBitmapRef