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Understanding Imager Resolution
Tip written by: Infraspection Institute

Resolution is one of the most important objective specifications for a thermal imaging system. Due to a lack of standardization, this term is used in a variety of ways, many of which can be confusing or misleading.

Simply stated, resolution describes the capability of a thermal imager to clearly depict a target. Imager resolution is determined by an interdependent set of circumstances, the most important of which are described below.

• Detector: Some manufacturers offer total pixel count of the detector as a measure of resolution. Resolution generally increases with the number of pixels; however, pixel viewing angle (IFOV) also affects detector resolution. Meaningful IFOV data are frequently unavailable.
• Optics: Changing lenses affects an imager’s ability to clearly resolve a target at a given distance. Generally, telescopic lenses increase optical resolution; wide angle lenses decrease resolution.
• Signal-to-noise ratio: Generally, higher ratios equate to increased image resolution. Imagers with poor ratios will provide imagery that is grainy, thereby compromising image quality.
• Display Monitor: To maximize performance, the pixel count of an imager display monitor should equal, or exceed the number of detector pixels. Compact or monocular displays can severely limit resolution. Use of a high resolution monitor cannot compensate for low detector resolution.

When considering an imager for purchase, be certain to try the imager under the same circumstances that you will encounter in the future. Because there is no objective method to determine imager resolution, one should physically compare subject imagers to each other.

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