What are thermal images?

Thermal images are much the same as regular images on a camera, other than the sensors used are either designed or have filters added to respond to a specific range of the light spectrum.

For instance, most of today's cameras have an infra-red filter built into them to specifically filter out the light range. However, if it's removed, it's possible to be able to take images based on the heat signature of the item being photographed. Although the sensitivity isn't the best, in most cases it'll work.

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Methinks the contributor doth confuse thermal with infra-red. I believe the above answer is true for digital cameras only, but such photos are not "thermal" images. Infra-red photography can also be practiced with a regular film camera, infra-red film and filters to enhance the result also. Either method requires light to be reflected from objects to the camera...a major difference.

Thermography is the rendering of images using only heat as the energy source, which is far below the capability of any light sensitive camera as far as I know. Such a camera has sensors which work whether visible light is present or not. If you can take your ordinary digital camera and render a picture outdoors at night with NO visible light whatsoever, I will eat humble pie. See this link for more on thermal imaging.

http://en.wikipedia.org/wiki/Thermography copyright ybarra-cgm
Micron

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