Archive for the ‘General Info’ Category

thermal-image-iron-palette

We have already talked about what are and how thermal cameras work, but now it is time to do a quick look at what do thermal images look like usually. Thermal cameras do not actually detect color as the infrared range they operate in is way beyond the range of the visible light, instead they record thermal information and that thermal information is then displayed in a way that we can visually interpret it in the form of an image. To make it easier for people to easily analyze a thermal image visually it is represented using a false colors representing the difference in temperature and the most commonly used color palette for that is the so called Iron one (shown above) where black is for the coldest areas, then blue and purple for slightly hotter areas, the mid-range of temperatures is usually red, orange and yellow and then going to white for the hottest parts. These false color visualizations usually do come with a small scale next to the image that show the colors used and what temperature range they cover as otherwise the person seeing a thermal image may get the wrong idea about the actual object temperature. It all depends on the temperature range that has been recorded, so black (the coldest part) on a thermal image can represent 0 degrees Celsius, 23.5 degrees C or another value and the same goes for the hottest and whitest part it could be 62.3 degrees Celsius or 200 degrees C. In thermal images using false colors to represent the difference in temperature there is no specific temperature representing specific color from the color palette used, the colors are just there to make it easy to distinguish the coldest from the hottest parts.

thermal-image-other-color-palettes

Another very common way is to represent a thermal image is in the form of a grayscale image, where you get only black to white colors passing through various levels of gray to represent the difference in temperature. This way of representing thermal images is often used in thermal security cameras or night vision thermal devices, but you will probably see it rarely used in other areas when thermal cameras are needed. The reason for that is, because it is harder for a normal person to distinguish the difference in temperature when only a single color is used and only the level of intensity is varied. It is much easier when you use a color palette with multiple colors. Aside from the most common Iron color palette that we’ve shown to you above here you can see some of the other often used false color representations used for thermal images. These are the Grayscale palette that we’ve already discussed as well as Arctic, Lava and Rainbow, and you may also find a versions of these with higher contrasting color palettes to make differences even more apparent. There of course could be thermal images using different color palettes as well, but as long as you have the smaller scale with the used colors and what temperatures they represent you should be able to quickly get an idea on what you are seeing in terms of temperature. Another interesting way of focusing the viewer’s attention to a specific area of the thermal image is to use grayscale thermal image with color only on specific areas that are either below or above certain temperature or if they fit in a specified thermal range.

flir-i7-thermal-imaging-camera

A thermographic camera, often also referred to as infrared camera (could be confused with digital cameras modified to take photos only in the infrared light spectrum), thermal imaging camera or just thermal camera is similar in design and functionality to a common digital camera, however there are some important differences. While most common digital cameras operate in the very narrow range of the visible light and barely touching some of the “invisible” Ultraviolet and Infrared ranges, thermal cameras operate in the invisible for the human eye infrared range and they can cover a really wide part of the electromagnetic spectrum. The process of taking thermal images with an thermal camera is referred as thermography and what the cameras essentially do is record the level of infrared radiation that an object emits. Thing get even better, because for taking thermal images you do not need to have visible light – thermal cameras can detect the emitted infrared radiation of objects in total darkness and thus their potential for different uses is extended even further.

thermal-image-of-a-computer-video-card

The thermal imaging sensors used in thermographic cameras do not distinguish colors as they are not operating in the visible light spectrum as we have already said, instead they record the level of infrared radiation emitted from the objects that the camera is pointed at. This essentially produces a monochromatic image with the intensity of a pseudo color representing different temperature (this type of visualization is often used in security thermal cameras). This however is not as easy to distinguish when you need to do thermal analysis, so various alternative methods of representation using false colors representing the difference in temperature as usually used. The most common visualizations of thermal images use black for the coldest areas, then going blue and purple for slightly hotter areas, the mid-range of temperatures is usually red, orange and yellow and going to white for the hottest parts. These false color visualizations usually do come with a small scale next to the image that show the colors used and what temperature the respective color stands for.

Usually thermal images are with a much lower resolution if you compare to what number of pixels the modern digital cameras provide, the reason is that the sensors used in thermal imaging cameras are much more expensive than what a sensor for recording the visible light costs. For example a 160×120 or 320×240 pixels thermal imaging sensors can be considered quite good and these usually are found in thermographic cameras that cost a few thousand dollars while as comparison we are already using multi-megapixel digital cameras in our smartphones with much higher resolution. Another important difference with thermal imaging cameras is that recording video is usually found in very high-end and pretty expensive models, it is not a common thing that you can find available on a more affordable thermal camera. Even if you manage to get a thermal imaging camera that supports video recording the chances are that it will record video at a much lower framerate than you probably are used in seeing in a normal video shot with a digital camera.

thermal-camera-image

We have always been fascinated with Thermal Imaging and Thermal Cameras as well as all other means of “seeing” the world around us in a different way that is simply not possible with what senses we humans have. This is one of the main reasons that we have created this project, as a means to play around, experiment and see things around us in a different way that what we see with our eyes and also to show it to you. For many people thermal vision or thermal images are directly being associated with one of the vision modes that the alien called Predator had in the movie series Predator. In fact our interest in thermal imaging is also related to the first Predator movie featuring Arnold Schwarzenegger from 1987, so it is not uncommon to often seen relations to this when talking about thermal imaging. Thermal cameras are becoming more and more accessible to people and they are finding their way in the hands of more normal people, although they are still used mostly by professionals for various work related tasks. But a thermal camera can be useful for a lot of thing and we are going to try to give you an idea for a few of these as well as to show you how common things look like when viewed with a thermal imaging camera, so stay tuned for some cool things to come.


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