The Time-Lapse FAQ
Chapter 6: The use of digital
Techniques to Deterring Time-Lapse Timing:
(How to calculate timing between exposures in Time-Lapse
photography for very difficult subjects)
By E.M. Kinsman Abstract: Sequential images captured electronically by a computer
from a video signal are analyzed using digital imaging techniques to determine
the difference between pixels. These difference are able to yield
timing and event information for difficult to photograph biological systems.
This techniques is described for the use with time-lapse cinematography.
Rochester Institute of Technology has made a program called CIS lab ( available
free at RIT center of Imaging site) which simplifies this process.
Procedure: A sequence of digital frame captures are made from a video camera. Each photograph is taken 15 minutes apart and digitized in the JPG format. The subject is a mushroom. Here is Image A ( time = 0 min) and Image B (time = 15 min)
the images are converted from their JPG compressed format into the BMP format where the mathematics will take place. Below is Image A (time = 0 min) Image B (time = 15 min)
Mathematically Image A - Image B is shown below. Zero difference between the images is set to a gray value Below is the difference between Image A and Image B showing the
change in 15 minutes time.
Below is the difference between Image A and Image C showing the change in 30 minutes time.
Below is the difference between Image A and Image D showing the change in 60 minutes time.
Below is the difference between Image A and Image E showing the change in 90 minutes time.
Below is a gif animation of what the final Time-Lapse will look like the time between images is 3 hours. The finished film is shot on 16 mm motion picture stock with an interval as determined above to be 15 min.
Click here to move to Chapter Seven of the Time-Lapse Photography FAQ |
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Kinsman Physics Productions • www.sciencephotography.com •
