Overlay transparent image in OpenCV

It seems OpenCV does not provide very much support for transparent images. It has images with 4 channels, which are treated as BGRA images, with the fourth channel being the Alpha channel. It also supports saving these images using the PNG format, yet it does not support properly displaying these images in highgui, nor does it support combining these images.

I have looked a while for a way to combine a (BGR) background image with a (BGRA) foreground image, with semi-transparent images, but was unable to find one. So, I wrote my own and since I couldn't find a solution on the internet, I'll bet I can save some people some time by sharing my implementation, which is as follows:

Installation guide: OpenCV 2.4 with Visual Studio C++ 2010

After some trouble installing OpenCV 2.4 in Windows and using it with Visual C++ 2010, I decided to write a post about this, so I can hopefully save you some time figuring this one out. It is based on this wiki, but that describes how to build with CMake etc, which is not necessary (anymore?).


Okay, so first you need to download OpenCV 2.4 here. After downloading, you need to extract it. I have extracted it to "D:\OpenCV2.4.2\" and I will use this folder for the rest of this post, you can change it if you like.

Edit your PATH variable (right click on this computer, properties, then select the tab "advanced" and click on "Environment Variables", which is near the bottom).

Add a Facebook "like" and Google "+1" button to Magento and integrate them with Google Analytics

Let's start with adding the Facebook like button. On this page: https://developers.facebook.com/docs/reference/plugins/like/, you can create the button as you would like it to appear on your site. When you press "Get Code", you'll get 2 pieces of code.

First we have to add the JavaScript code. To do this, open your head.phtml page, which can be found here:
app/design/frontend/<your template>/<theme>/template/page/html/head.phtml

In this file, add the script, like so:

<script type="text/javascript">
  (function(d, s, id) {
    var js, fjs = d.getElementsByTagName(s)[0];
    if (d.getElementById(id)) return;
    js = d.createElement(s); js.id = id;
    js.src = "//connect.facebook.net/nl_NL/all.js#xfbml=1";
    fjs.parentNode.insertBefore(js, fjs);
  }(document, 'script', 'facebook-jssdk'));
</script>

After that, you can add the other part of the Facebook code in any of your pages, where you would like to have the button. If you want to have it in a CMS page, you can create a Custom Variable, by opening the admin part of your Magento shop and navigating to System -> Custom Variables. In there, create a new variable and insert the code in the Variable HTML Value.