Wednesday, July 22, 2009

The invisible flash

Using the flash while taking some photos may be, in some situations, the only choice you have in order to produce decent lighting in a picture. However, most flash pictures are ruined because of the excessive light in the foreground and not enough light on the background.

In the ideal world of photography, a camera would be able to capture just enough light to make the picture perfect but not suffer from the disadvantages of using flash. Basically, what we need is an "invisible flash". But how can one produce such a paradox: a blast of light but that is not visible?

The answer is given by a student of the New York University, Dilip Krishnan and his advisor Rob Fergus. They have developed a dark or invisible flash which uses infrared and UV light to take photos in dark places without the nasty glare of a standard flash.

Basically, what they did was modify a light bulb to emit light over a wider range of frequencies (not visible at the human eye). They also changed their camera to adapt to these new conditions by using a set of filters to prevent the silicon image sensor from detecting infrared and ultraviolet rays.

This is not exactly new as this is more or less like night vision works. The difference is that, instead of having those photos where we all look like vampires, they managed to find a way to produce the correct colour balance by taking a quick colour image right after the dark flash image.

Even though the image produced in this second image is of low quality (grainy and unclear), the colours are correct. This allows them to produce a correct final image by using special software that combines the information from the photos (you can see the process on the 3 images above).

The technology is not yet perfect but it definitely looks pretty promising. To know more about it, you can check the website here.

Source: Engadget