README: fix a typo s/has showed/has shown/

[experiments/opencv_trail_effect.git] / README

diff --git a/README b/README
index cd242b0..1672722 100644 (file)
--- a/README
+++ b/README
@@ -11,15 +11,20 @@ Some examples of it are:
   Elisa - L'Anima Vola - https://www.youtube.com/watch?v=MqhxIQD16EA
 
 opencv_trail_effect draws a trail after performing foreground segmentation
-(using thresholding or background subtraction) using OpenCV.
+using OpenCV.
 
-The "sole" assumptions for a decent effect are that:
+Segmentation in opencv_trail_effect can done using either thresholding or
+background subtraction.
 
-  1. the camera does not move;
-  2. the background lighting in the scene is quite stable (when doing
-     background subtraction it is recommended to disable auto-gain in the
-     camera, and avoiding any artifact introduced by the power line
-     frequency).
+A few conditions are required to create a decent effect:
+
+  1. the camera should not move;
+  2. the lighting in the scene should be quite stable (when doing background
+     subtraction it is recommended to disable auto-gain in the camera, and
+     avoid any artifact introduced by the power line frequency);
+  3. the subject should enter the scene only after the background learning
+     phase has finished, i.e. after opencv_trail_effect has shown the preview
+     window.
 
 
 Examples of use
@@ -49,6 +54,8 @@ frames in the trail, possibly with the most recent frame drawn on top:
 
   $ ./opencv_trail_effect -l 10 -s background -d average -B
 
+Here is a video showing the examples from above:
+https://www.youtube.com/watch?v=X3oRozxt2O4
 
 Side note
 -------------------