The ability to capture images of ultrafast phenomena could help scientists to understand them better. A new development in virtual time lapse imaging could revolutionise this process.
Natural and industrial phenomena can occur very quickly. The drawbacks of current imaging technology has led to scientists at the EPFL’s Engineering Mechanics of Soft Interfaces Laboratory, working with Harvard University researchers, to develop new virtual time lapse imaging technology.
The cons of current technology
The L’Ecole polytechnique fédérale de Lausanne (EPFL) gave some examples of ultrafast phenomena in industry and nature, such as:
•A tear running through a piece of fabric;
•A rubber ball bouncing off a hard floor;
•A drop of water wetting a dry surface; and
•A piece of scotch tape peeling off.
Currently, conventional cameras are not fast enough, and although high-speed cameras can be used to capture ultrafast phenomena, these are prohibitively expensive.
The new technique
John Kolinski, a professor at EPFL’s School of Engineering, “If you use a regular camera to take a picture of a drop of water hitting a dry surface, the water’s movement will cause the picture to be blurry. But these blurred areas are precisely where the phenomenon is taking place, both spatially and temporally. That’s what our technique uses to piece together the underlying phenomenon.”
The first step of the process is shining light on the phenomenon as the conventional image is taken, to exploit the blurry parts of the image. Kolinski added: “This initial illumination step must be done correctly so that the blurry parts of the picture contain the right information and can be used. At this point the object must have a quantifiable instantaneous state of either completely blocking the light or completely letting it through”.
Then, advanced image-processing methods are employed to improve the temporal resolution and specific illumination scheme. The image is turned into a binary image, containing either black or white pixels.
Binary images in phenomena and technology
Many natural phenomena are binary, with only two greyscale values necessary for depiction, which means this method is advantageous. By focusing on the bit depth instead of resolving intensity, the scientists have been able to increase the frame rate while maintaining full spatial resolution of the image.