Saturday, July 19, 2014

BackBlog - Teleporter video

We through a Star Trek themed surprise party for my wife and I thought it would be fun to see if I could make a transporter effect.
To start we took two pictures, one with everyone in an away team formation and one with just the background

I then wrote a simple program to add the two images together using a weighted sum.  This technique looked okay but I also wanted some noise.  I used the matlab imnoise function to create some sparkles. Inicially just a few, grow to a lot about halfway and then disparate as the people materialize.  

The trick is to get the speckles to only appear where there are people.  I could have tried some clever image subtraction trick to find the region that changed but it was just as quick for me to use GIMP to cut the people out and make a simple flag array using the following Matlab code.  I had to also use GIMP to paint over any white spots in the image. Fortunately for my image there was very little white. I ended up with the following (I guess I could also have just select the white and set everything else to black).

Now, potting All the components together and looping from 0 to 100 I was able to create a directory of images that I wanted and stitched the images together using ffmpeg.

To top it off,  I found a transporter like sound on the net and used my copy of Camtacia ( to put the audio and video together.
Here is my final product:


- Dirk