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Emerald Group Publishing Limited
Copyright © 2008, Emerald Group Publishing Limited
Article Type: Editorial From: Sensor Review, Volume 28, Issue 3
The field of electromagnetic sensors is certainly very broad. It includes the visible spectrum, UV, IR, X-rays and γ-rays, and radio in all its wavelengths. It also concerns a wide variety of sources – some objects emit this radiation while others merely reflect various parts of the electromagnetic spectrum that fall on them.
One difficulty that we have with electromagnetic radiation is that as humans we are only sensitive to a very small percentage of it. We can see in the visible spectrum and feel the effects of infrared and of ultraviolet but we are insensitive or blind to other frequencies.
We will all have been amazed at the wonderful images of galaxies brought to us by the Hubble Telescope (http://hubblesite.org), however we are only shown the artistic end result after the black and white images that the Hubble produces have been “improved” by image processing to enable us to see the UV, visible and IR radiation.
The images that are released to the public are not exactly fakes but they are not exactly real either. Enhancement allows us to see structures that would otherwise be hidden from our eyes (Figure 1).
Figure 1 V838 monocerotis light echo
The same can be said for thermal imaging cameras that can be used to “see in the dark” or to measure the temperature of what they are looking at. By basically adjusting or re-mapping the wavelengths of the electromagnetic spectrum, human beings are able to visualize the structures in the scene and this goes a long way towards helping our understanding of what we are looking at.
Image processing and understanding is one of the few areas in which people are significantly better than computers, although the gap is narrowing fast. It therefore makes sense for us to experiment with different visualizations of the data that is presented to us. Many problems can seem intractable when viewed from one perspective and yet they can sometimes be easily solved if we simply view them in a different light.
As a simple example, the use of colour can make it relatively easy to spot strawberries in a field of green leaves. Similarly, the polarization of emitted or reflected radiation can be used to highlight differences that are otherwise invisible, as anyone looking through a toughened glass windscreen while wearing sunglasses will be able to tell you.
Next time you are having difficulty separating the wood from the trees, try viewing it from a different part of the spectrum.