Posts Tagged ‘thermal image


If you are taking thermal images of various things you should be well aware of the fact that while thermal images do show the temperature of objects they do little to provide easy visual cues to what part of the object is hotter or colder. The reason is that thermal images just record the temperature information of objects and while this can create somewhat of an outline of the object you are examining, if you do not take a visual image to store with the thermal image later on you might have trouble identifying things on the thermal image. Not all thermal cameras ca do that – record both thermal and visual images, but even if your camera does not support that (like our FLIR i7 for example) you can still do pretty well if you use a digital camera or your smartphone to also take a visual image as a reference.

Thermal MSX (Multi Spectral Dynamic Imaging) images is what FLIR calls their mode of overlaying both thermal and visual images together and processing the data in order to provide a more detailed thermal image and this mode does work very well as you can see on the sample image above. Even with lower resolution thermal image when you overlay on top of it a visual image and combine the two to have the outlines of the objects you are shooting the end result can be really good. On this thermal photo we have recorded the temperature of an Mitsubishi Air-conditioning system in operation shot with the FLIR ONE thermal camera accessory for iPhone. Even though the FLIR ONE is with a low resolution thermal imaging sensor when we combine the thermal with visual information the resulting thermal MSX image does look really good as it can give both useful thermal and visual information, especially if the goal of the image is to be more understandable to people that are new to thermal imaging.

Taking MSX thermal images (overlaid visual and thermal data) however is not possible all the time as taking a good image in the visual light spectrum does require you to have good light conditions, unlike thermal images that can be taken even during total darkness. So make sure that you have enough light available when you need to take MSX thermal images if you have a thermal camera capable of this as not all models can do this, but as we’ve explained you can help yourself by taking manually a visible spectrum photo with the help of your smartphone or digital 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.


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.