Higher Resolution Imagers – What You Really Need to Know
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Higher Resolution Imagers – What You Really Need to Know
The recent introduction of 640 x 480 pixel imagers has many thermographers speculating on the impact this equipment will have on our industry and their business. In this Tip we separate marketing hype from physics by revisiting the issue of resolution and its importance in thermal imaging.
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 not solely dependent upon pixel count. Rather, it is determined by an interdependent set of circumstances, the most important of which are described below.
- Detector: Many 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: Lens quality affects an imager’s ability to clearly resolve a target at a given distance. With no industry standard for optics, lenses can vary widely between imagers.
- 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 resolution, 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, do not rely on pixel count as an accurate representation of imager resolution. Always 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 and choose the one that meets their needs and budget.
To better understand imager resolution, read the article, Selecting, Specifying and Purchasing Thermal Imagers available from Infraspection Institute. To obtain a copy of the article, call 609-239-4788 or visit us online at www.infraspection.com.
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