From 47fc889df0ed25b05c43106c8e2342e6ebb8b0e1 Mon Sep 17 00:00:00 2001
From: JamesNewton <jamesnewton@massmind.org>
Date: Fri, 11 Oct 2019 10:07:22 -0700
Subject: [PATCH] Update js_image_arithmetics.markdown

---
 .../js_image_arithmetics/js_image_arithmetics.markdown        | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/doc/js_tutorials/js_core/js_image_arithmetics/js_image_arithmetics.markdown b/doc/js_tutorials/js_core/js_image_arithmetics/js_image_arithmetics.markdown
index 73e483943d..30ed918576 100644
--- a/doc/js_tutorials/js_core/js_image_arithmetics/js_image_arithmetics.markdown
+++ b/doc/js_tutorials/js_core/js_image_arithmetics/js_image_arithmetics.markdown
@@ -27,7 +27,7 @@ src1.delete(); src2.delete(); dst.delete(); mask.delete();
 Image Subtraction
 --------------
 
-You can subtract two images by OpenCV function, cv.subtract(). res = img1 - img2. Both images should be of same depth and type.
+You can subtract two images by OpenCV function, cv.subtract(). res = img1 - img2. Both images should be of same depth and type. Note that when used with RGBA images, the alpha channel is also subtracted.
 
 For example, consider below sample:
 @code{.js}
@@ -59,4 +59,4 @@ Try it
 <iframe src="../../js_image_arithmetics_bitwise.html" width="100%"
         onload="this.style.height=this.contentDocument.body.scrollHeight +'px';">
 </iframe>
-\endhtmlonly
\ No newline at end of file
+\endhtmlonly