How to Adjust a Thermal Camera to Detect Only Human Body Temperature
In today's world, thermal cameras have become indispensable tools in various applications, from medical diagnostics to security. However, detecting only the temperature of the human body and not any other object can be challenging. This guide will help you achieve this by understanding the basics of thermal imaging and adjusting the settings correctly.
Understanding Thermal Imaging
Thermal cameras, or infrared cameras, do not measure temperature directly but instead detect the infrared radiation emitted by objects. These cameras convert this radiation into temperature readings, providing a visual representation of heat distribution.
Why Adjust Your Thermal Camera?
When using a thermal camera, simply turning it on usually won't give you the temperature of a human body accurately. This is because most thermal cameras require calibration to focus on the specific temperature range of human skin. By adjusting the settings, you can ensure that the camera only detects and displays the temperature of the human body without interference from other objects or background noise.
Steps to Adjust a Thermal Camera
1. Disable Auto Functionality
First, turn off the Auto function if your thermal camera has one. If the camera automatically adjusts the settings based on background temperature, you will inevitably end up with a washed-out, poorly detailed image of the human body. Low-end thermal cameras often lack this functionality, resulting in images that cannot be properly focused on the human body.
2. Adjust the Span and Level Settings
Next, switch to a manual adjustment mode if available. In Range 1, adjust the Span and Level settings until you can clearly see the body. Setting the Span too wide or too narrow can result in either a washed-out image or one that shows the background temperature.
For example, in the first image below, the Span has been set too wide (19–38°C). This setting will show the background at 24°C and is set too high (38°C) for the body temperature of approximately 36.7°C. This means the background will show in the image, and the face details will be unclear.
Image 2 below shows the same image properly adjusted to remove the background (27.8°C) and show thermal details on the face (36.6°C).
Setting Emissivity
When monitoring the human body temperature, emissivity is a crucial setting. Emissivity refers to the ability of a material to emit thermal energy. For a basic thermal image and not for temperature measurement, emissivity and other temperature settings like reflectivity, transmissivity, relative humidity, and distance are not critical as they do not change the image details, just the temperature readings. Leave the emissivity setting at 0.98, which is the standard value for human skin.
Common Settings and Their Usage
Most thermal cameras have several settings, with many of them being automated. However, body temperature or any reference temperature is not typically one of these automatic settings. Understanding and adjusting the following settings can help you get accurate temperature readings of the human body:
Emissivity: Set to 0.98 for human skin.
Span: Adjust to include the temperature range of the human body, typically around 36-37°C.
Level: Adjust to enhance detail and clarity of the human body in the image.
Range: Ensure it's set to a safe level to avoid saturating the image with white spots, which can indicate an over-exposure.
Conclusion
To summarize, adjusting your thermal camera to detect only the temperature of the human body requires disabling automated functions, manually adjusting the Span and Level, and setting the emissivity to 0.98. By following these steps, you can ensure that your thermal camera provides accurate and detailed temperature readings of the human body, useful in a wide range of applications.