Focus is the most important (and most difficult) factor in thermal image accuracy, so it’s worth the time to get the most accurate image you can with your infrared camera. Here are a few reminders of how to boost that accuracy:
Focus on the details
If you’re like a lot of experienced thermographers, you probably like to manually focus your thermal imager. You know exactly how to get the level of detail you’re looking for. Here are some additional tips that might help you get expedite that manual focusing task:
- Start with a monochromatic color palette because the human eye typically can focus in black and white (gray scale) or black and yellow (amber) more easily than in full-color scales.
- Look for a sharp edge in the field of view at the same distance as your target and focus on that first.
Laser-assisted auto focus saves even more time. You can use the laser distance meter to calculate and display the distance to the target, and the focus engine does the precise focusing for you. Some cameras go even further with multifocal capture that records multiple images from varying focal distances and then uses specialized software to combine all those images into one image with extra sharp depth of field detail.
Zero in on resolution and field of view (FOV)
As you know, resolution comes in two flavors—detector (measured in pixels) and spatial (measured in mRads). Each detector pixel detects the apparent temperature of its area of the target, so the more pixels, the higher the detector resolution, the more accurate your image. Spatial resolution combines that detector resolution with the field of view (FOV) spec to define the area the imager sees at any given moment. Spatial resolution can be used to help define the smallest object size that can be detected. The lower the spatial resolution value, the better the detail and image quality.