From: Antonio Ospite <ao2@ao2.it>
Date: Thu, 22 Feb 2018 12:12:04 +0000 (+0100)
Subject: opencv_trail_effect.cpp: fix showing the background
X-Git-Url: https://git.ao2.it/experiments/opencv_trail_effect.git/commitdiff_plain/5ac5412e847a0abaeaf83c3a0299e68ffaec10f1?ds=inline;hp=5ac5412e847a0abaeaf83c3a0299e68ffaec10f1

opencv_trail_effect.cpp: fix showing the background

When showing the background OpenCV would fail with this message:

  OpenCV Error: Assertion failed (channels() == CV_MAT_CN(dtype)) in copyTo, file /build/opencv-lY8WRY/opencv-3.2.0+dfsg/modules/core/src/copy.cpp, line 259
  terminate called after throwing an instance of 'cv::Exception'
    what():  /build/opencv-lY8WRY/opencv-3.2.0+dfsg/modules/core/src/copy.cpp:259: error: (-215) channels() == CV_MAT_CN(dtype) in function copyTo

Initializing the background to the same format of the input frame seems
to fix this.
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