Smoke measurements 

What comes to mind first when thinking about smoke experiments are those cool pictures where the smoke path is clearly visible, right? 
Well, visualizing smoke clearly is more difficult than you presume.  

As you maybe have read in the blog ‘The struggles of experiments’ we created a special setup to visualize smoke.
The background of our face mold Veronica was made completely black by hanging curtains from the ceiling. On both sides of the face molds, flashlights were set up and placed at such an angle that the background was not illuminated. After taking a lot of shots, we optimized the position of the flash lights in combination with the correct settings of the camera. We took it from here and started the measurements of the actual experiments! 

To capture the smoke release of the masks, photos were taken during exhalation. During the analysis of these experimental results, we investigated the changes in an image with respect to a reference image. That means that if only smoke was visible in the frame of a photo this will be visual in the final analyzed photo. This analyzed photo was used to measure results.
However, it wasn’t easy to obtain just smoke from the images. Images were not always perfectly aligned with respect to a reference image, so image processing was applied to improve this alignment. 

Because the majority of an analyzed picture is black, it is hard to detect the smoke by a human-eye on a laptop screen, but we knew it was in there when processing our results. 
For our own insight, we played with the brightness and contrast of some pictures and sometimes we were shocked by the smoke that was actually in the picture!

  All in all, it was a long way from gathering data to getting results, but we made it!