Expert Contributor:
Riccardo Tamburini
When it comes to thermal imaging, image quality isn’t defined by a single number. It’s the result of how several specifications work together. Resolution, pixel pitch, and NETD may sound like technical jargon, but for hunters, these parameters decide whether a distant heat signature appears as a vague blur or a clearly defined target.
Pulsar, a leader in European thermal imaging technology, designs its devices around this balance, optimizing sensor architecture and in-house processing to deliver sharp, high-contrast visuals in any light or weather.
This thermal sensor guide breaks down how each specification affects real thermal performance. Our aim is to help you understand what truly matters behind the numbers and why some devices outperform others in the field.
Quick answer
True thermal image quality isn’t defined by a single number — it’s created through synergy between resolution, pixel pitch, and NETD, refined by Pulsar’s proprietary image processing and system-level calibration (sNETD).
- Resolution defines image structure and contour precision.
- Pixel pitch determines how finely textures and edges are captured.
- NETD measures thermal sensitivity — the lower the value, the better the contrast in fog, rain, or cold dawn air.
Pulsar goes beyond standard NETD by introducing sNETD (System NETD) — a real-world performance metric that includes not just the sensor, but also optics, electronics, and image algorithms. This ensures every device reflects true sensitivity and clarity in actual hunting conditions, not just laboratory tests.
Key takeaways
- Thermal image quality = balance, not one specification. Resolution, pixel pitch, and NETD work together to define detection precision and contrast.
- Resolution (e.g., 640×480) captures more thermal data for cleaner, sharper contours and better zoom quality.
- Pixel pitch:
12 µm → captures finer details, enables lighter and more compact designs.
17 µm → increases sensitivity in unfavorable conditions (fog, rain, humidity).
- Low NETD (<25 mK) → higher sensitivity and contrast in low-visibility weather (fog, rain, dawn).
- Why Pulsar uses sNETD: Unlike conventional NETD that measures only the sensor, sNETD represents the entire system’s thermal sensitivity — factoring in optics, electronics, and processing. This gives a truer reflection of field performance and ensures consistency across models.
- Pulsar image processing — Image Detail Boost and Dynamic Contrast Adaptation — further enhance micro-contrast, edge clarity, and visibility.
- Best practice: Choose specs based on hunting style and terrain:
12 µm for compact precision in dense cover.
17 µm for better perfomance in humid conditions.
<25 mK NETD (with sNETD optimization) for challenging, low-contrast environments.
How thermal sensor specs define real image quality
Image quality in a thermal monocular depends on the balance between sensor resolution, pixel pitch (µm), and NETD sensitivity. Higher resolution captures more detail, smaller pixel pitch increases sharpness, and lower NETD improves contrast in low-visibility conditions. The best performance comes from optimizing all three.
Many hunters get caught in the 12 µm vs 17 µm debate, focusing on a single number instead of the full picture. In reality, image clarity depends on how these factors interact. A 640×480 sensor with 12 µm pixels and a NETD below 25 mK delivers both fine detail and strong contrast, but only when the optics and processing are equally well-tuned.
That’s why Pulsar designs every device as a complete imaging system, ensuring consistent clarity and precision across its thermal line-up, from compact Axion models to flagship Telos LRF XP50.
Read more: Pixel pitch, explained | 12 µm vs. 17 µm
Tip from the field – our expert Riccardo Tamburini shares his approach towards choosing a thermal sensor that’s right for you:
It would be super if the performance of a thermal device depend on a single feature. A thermal unit is complex and made from a lot of components often linked between each other; of course, knowing the real NETD, the resolution of sensor or the pixel pitch is already a good starting point but, for example, a low NETD with a lens aperture greater than f1.0, is the classic case of having a Ferrari with the wheels of a bicycle!
A user should know how the most important features work all together but I know it’s not easy. The resolution of the sensor drives the choice many times, but a user should know that the pixel pitch could be important as well: 12µm is better when looking for small hot targets quite far from the observer because a smaller pixel pitch will offer a more sharpen image at good distance, but if you are looking for a more versatile device, 17µm will perform better.
A user should see the pixel pitch like a box: bigger is the box, bigger will be the amount of things it can be stored inside; having a very super low real NETD with a lens aperture of f1.0 and a pixel pitch of 12 µm is a nonsense: a 17µm will be better because it will be possible to store more info inside! And displaying more info even means being able to see the smaller differences of temperatures in the environment we are scanning. If you need a thermal unit able to properly work in different scenarios, with different weather conditions at different distances, go to 17µm with a low NETD and lens aperture of f1.0.
What affects thermal image quality the most — resolution, pixel pitch, or NETD?
To evaluate any thermal device correctly, you must understand three core specifications that shape every image: resolution, pixel pitch, and NETD. Each plays a distinct role and it’s their interaction that ultimately defines how clearly you can detect, recognize, and identify a target in the field.
Resolution: how much detail the sensor can see
Resolution defines how many thermal pixels capture heat signatures on the sensor. A higher resolution, such as 1024×768, records more thermal data, resulting in sharper outlines, cleaner contours, and better object separation, especially when zooming in.
By contrast, a 384×288 sensor provides a more compact and efficient setup, ideal for short- to mid-range detection with faster processing and lower power use.
In practical terms, higher resolution means more freedom to use digital zoom without losing too much clarity. For example, Pulsar’s Thermion 2 LRF XL60, with its 1024×768 sensor, offers exceptional precision for spotting fine textures like fur or antlers even at long distances.
Pixel pitch: the distance between each pixel
Pixel pitch, measured in micrometres (µm), is the distance from the center of a pixel to the center of the adjacent pixel. It indicates how closely packed the pixels are on the sensor surface. A smaller pitch (typically 12 µm) increases pixel density, producing sharper, more detailed images. It also enables the use of smaller lenses, making devices more compact and lightweight.
However, larger pixels, such as 17 µm, have a greater surface area and can absorb more infrared radiation. This can enhance thermal sensitivity, especially when visibility is poor or contrast between objects and background is minimal.
This is why Pulsar uses both 12 µm and 17 µm sensors across its range: to offer different balances between compactness, detail, and detection stability depending on the device’s purpose.
Note: Sometimes, pixel pitch is defined as a pixel size. However, this is mostly used in an everyday, non-professional sense, and is therefore not a correct definition for a precise evaluation of a sensor.
NETD: the sensor’s sensitivity to tiny temperature differences
NETD (Noise Equivalent Temperature Difference) measures how sensitive a thermal sensor is to temperature variations, expressed in millikelvins (mK). It represents the smallest temperature difference the sensor can detect — the lower the value, the higher the sensitivity.
A sensor with NETD <25 mK can distinguish minute heat differences between an animal and its surroundings, delivering crisp, high-contrast images even in rain, fog, or cold dawn air. Devices like the Pulsar Telos LRF XP50 or Thermion 2 LRF XP50 Pro exemplify this capability, revealing subtle details that higher-NETD sensors might miss.
Together, these three parameters define the visual precision of any thermal optic. But what truly separates one device from another is how these values are tuned to work as one balanced system.
Learn more: Dive deeper into the main parameters of thermal imaging devices.
Pixel pitch vs resolution — which one matters more?
A smaller pixel pitch (12 µm) usually delivers sharper images with finer detail, while a larger pitch (17 µm) can perform better in low-contrast. Both are essential, and understanding how they work together helps hunters choose the right thermal device for their environment.
Smaller pixels mean tighter detail and lighter optics
When pixels are closer together, the sensor captures more detail per square millimetre. A 12 µm pixel pitch increases image sharpness and allows manufacturers to use smaller, lighter lenses without losing detection range.
This combination leads to more compact and portable devices — a key advantage for mobile hunters who need agility and fast scanning. For instance, Pulsar’s Axion XG35, with its 640×480 @ 12 µm sensor, offers crisp image precision in a pocket-sized format.
Larger pixels capture more energy and improve sensitivity
A 17 µm pixel is physically larger, meaning it can absorb more long-wave infrared radiation. This greater energy capture enhances thermal sensitivity and can deliver stronger performance in fog, rain, or cold environments where thermal contrast is low.
Devices using 17 µm sensors tend to offer smoother detection in tough conditions, maintaining visibility even when smaller-pitch sensors might struggle with background noise. The Pulsar Telos XQ35, featuring a 384×288 @ 17 µm sensor, exemplifies this balance, prioritizing thermal sensitivity and compactness over large detection range.
Image quality depends on more than pixel size
While pixel pitch influences how the image looks, it’s only one part of the system. Lens quality, sensor architecture, and image-processing algorithms play equal roles in determining clarity and contrast.
Pulsar’s integrated design approach ensures that both 12 µm and 17 µm sensors perform consistently across models, thanks to advanced processing tools like Image Detail Boost and Dynamic Contrast Adaptation.
Real-world comparison: Axion XG35 Compact vs Telos XQ35
- Pulsar Axion XG35 Compact: 640×480 @ 12 µm: Delivers sharper fine detail and a compact build ideal for short- to mid-range scanning.
- Pulsar Telos XQ35: 384×288 @ 17 µm: Offers steady poor weather detection and better performance in low-contrast weather conditions.
In short, smaller pixels favor image precision and portability, while larger pixels enhance sensitivity and detection stability. The best choice depends on where and how you hunt — dense woodland, open fields, or variable terrain. Here’s what Riccardo advises:
The Telos XQ35 is very helpful in mountain hunting. Its size allows me to store it in the pocket of by backpack, always ready-to-use. I don’t need a super clarity, but I need a thermal device which helps me save time looking for far chamois. Often trough a dense fog. Once spotted a herd, I always have a standard bino or a spotting scope with me to make a deeper analysis about sex, class age and status of each single animals in the herd, before to see if there is one corresponding to the tag I have.
The Axion XG35 Compact is my favourite when I’m out looking for targets in the woods. The squirrel control is more efficient at the end of November or December because it’s their spawning season. During winter, the detection of these animals is easier because there’s no leaves on the trees, but I need a thermal unit able to detect a small target, sometime multiple targets in hard circumstances; this is why I prefer having a good base magnification. In this scenario, I don’t need a device with a super sensitivity because often the background is the sky, because the squirrels live on the high branches of the trees.
The role of NETD — seeing the invisible in rain, fog, and cold
NETD defines how sensitive a thermal sensor is to temperature differences. A lower NETD (for example, <25 mK) means the device can detect smaller heat variations, producing clearer, more detailed contrast. This sensitivity becomes critical in fog, rain, or low-temperature environments, where thermal differences are minimal and visibility is reduced.
Why low NETD = high contrast
A low NETD value indicates that the sensor can register even the slightest temperature difference between an object and its background. This sensitivity translates to sharper, more detailed images when thermal contrast is poor — at dawn, dusk, or during humid and rainy conditions.
For hunters, that means being able to distinguish animal outlines, body contours, and terrain texture when other sensors would only show faint silhouettes.
NETD <25 mK vs <40 mK in real-world use
A sensor rated <25 mK delivers a clear advantage over one rated <40 mK, especially in challenging conditions. The difference becomes visible when scanning through fog or observing partially obscured targets, making subtle contours, fur texture, or movement easier to identify.
Devices like the Pulsar Axion XQ19 Compact or Merger LRF XP35 use <18 mK sNETD sensors to retain fine detail where lesser systems lose contrast, ensuring dependable visibility even in unstable weather.
How Pulsar’s Image Detail Boost enhances visibility
Pulsar doesn’t rely on hardware alone. Its proprietary Image Detail Boost algorithms dynamically sharpen micro-contrast and edge definition in real time. Working alongside low-NETD sensors with high thermal sensitivity, this software ensures that even small heat variations stand out clearly.
The result is consistent clarity across all Pulsar devices, giving hunters confidence that they’re seeing the complete picture, not just an outline.
NETD vs sNETD — Understanding the difference
While NETD (Noise Equivalent Temperature Difference) measures the sensitivity of the sensor itself, Pulsar takes accuracy further with a more advanced metric: sNETD (System NETD).
NETD, or Sensor NETD, evaluates only the microbolometer — the heart of the thermal sensor — under controlled lab conditions. It doesn’t account for external factors such as lens quality, image processing, or display performance.
sNETD, or System NETD, measures the entire device’s thermal sensitivity, combining the effects of the sensor, optics, electronic signal processing, and Pulsar’s proprietary image algorithms.
Because it reflects real-world operating conditions, sNETD gives a more realistic picture of how a device performs in the field. In short, Pulsar’s sNETD rating represents total system performance, ensuring users experience precise contrast, stable detail, and true image fidelity in every environment. For a practical insight, we turn to Riccardo:
Pulsar is the sole company in the market which spends its time trying to describe the difference between NETD and sNETD; why is it important knowing both of numbers?
The NETD, or the real sensitivity value, gives to the user the possibility to better understand how good the used components are. The sNETD measures how big was the software manipulation and, as we’ll see, this value has a big impact on the overall performance of a thermal device.
The problem is that a user won’t ever know which NETD the Pulsar competitors use: the real NETD, or the NETD calculated considering the altering made from the algorithm? Don’t worry, there is a trick to know before purchasing a thermal unit in a shop – I’m sharing it below.
Read more: NETD vs sNETD: What’s the difference?
Why do two devices with similar specs show different image quality?
Two thermal devices can share identical specifications — the same resolution, pixel pitch, and NETD — yet deliver noticeably different images. That’s because image quality depends on the entire imaging system, not just the sensor.
The final result is influenced by multiple factors:
- lens quality, which affects how infrared radiation reaches the sensor;
- display resolution, which determines how clearly the processed image appears;
- and image algorithms, which control contrast, sharpness, and detail enhancement.
Note: Display resolution definitely should not be lower than the sensor resolution (the display must not degrade the image produced by the sensor). The higher the display resolution, the higher the quality and the more complex the overlay graphics can be.
Even housing temperature can alter performance, as internal heat may affect sensor stability during prolonged use.
Pulsar addresses all these variables by engineering hardware and software as a single, integrated system. Its sNETD value already reflects total performance, factoring in real-world operation and image optimization. Technologies like Image Boost and Dynamic Contrast Adaptation further refine the image, ensuring consistent clarity and definition across different models and weather conditions.
How Pulsar balances sensor specs with image processing
Thermal imaging performance is not defined by numbers alone. While resolution, pixel pitch, and NETD set the foundation, software processing determines how those specs translate into what hunters actually see in the field.
Pulsar’s integrated performance philosophy treats every device as a unified imaging system, where hardware and algorithms work together to deliver consistent, lifelike visuals.
Why processing matters as much as sensor data
Even the best sensor can only capture raw thermal information. Without intelligent processing, that data lacks definition and contrast. Pulsar’s software bridges this gap, refining sensor input to create a clear, stable, and high-contrast image in real time.
Pulsar’s proprietary algorithms
To achieve optimal clarity across all models — from compact monoculars to flagship riflescopes — Pulsar relies on two core image-processing technologies:
- Image Boost / Image Detail Boost: These dynamic sharpening tools enhance micro-contrast and edge precision, revealing fine textures such as fur, foliage, and terrain contours. They automatically adapt to the scene, ensuring visible detail even in fog, drizzle, or low-temperature differences.
- Dynamic Contrast Adaptation: This feature adjusts brightness and contrast levels frame by frame, maintaining visibility in both high- and low-contrast environments. It prevents image washout when transitioning from open fields to shaded woodland, or when ambient temperature shifts during the hunt.
Note: there’s a fine balance between using the algorithms to improve the image, and overusing them to a point where the image quality actually decreases. Riccardo describes the issue as follows:
So, here’s the promissed trick how a user can easily understand if the thermal device has a declared value of NETD or sNETD: NETD is a value calculated on the sensor, not gotten after a software manipulating as sNETD.
Altering the result about what the user will see through the display of the thermal unit needs time: the time spent to alter the final image. Often, it is a very small amount of time but it’s enough to introduce a delay in the transmission of images from the reality. This delay is called latency. On the market, there are devices with up to 0.6 second of latency: shooting at small targets it could be the difference between a good shot and a missing one.
Verifying latency is easy: having both eyes opened, a user should see through the eyepiece with one eye on a moving target in the display and with the other eye on what is happening to the same target in the reality: if the real movement and what is displayed on the monitor are synchro, there’s no latency. If there is a delay, it would be better to choose another thermal device.
A balanced system for every sensor type
These algorithms enhance both high- and low-resolution sensors, ensuring that devices with 384×288 sensors perform well beyond what their raw specs suggest, while 640×480 models reach their full potential in fine detail reproduction.
The result is consistent image quality across Pulsar’s entire range, allowing hunters to trust what they see, regardless of terrain, temperature, or lighting conditions.
Real-world scenarios — Which sensor fits your hunting style?
Different environments favor different sensor configurations. The right balance of resolution, pixel pitch, and NETD depends on where, when, and how you hunt. Pulsar’s wide range of devices is designed to match each setting, ensuring you get the clearest, most reliable image under any conditions.
Dense forest and short to mid-range scouting
In dense woodland or brush, hunters often face limited visibility and shorter detection distances. A higher resolution combined with a smaller 12 µm pixel pitch captures more fine detail, revealing subtle movement between branches or tall grass.
The Pulsar Axion XG35 Compact, featuring a 640×480 @ 12 µm sensor, excels here. It is compact, fast, and accurate for agile stalk hunting.
Open fields and poor weather conditions
When scanning across wide, open plains or agricultural fields, larger 17 µm pixels paired with high sensitivity provide better stability and detection at humid conditions. These sensors absorb more infrared energy, producing cleaner contrast over distance and in minimal heat variation.
The Pulsar Telos XQ35, with its 384×288 @ 17 µm configuration, offers dependable range and strong thermal response in open terrain, making it ideal for both stationary glassing and on-the-go observation.
Adverse weather and cold mornings
During fog, rain, or early dawn, when temperature differences between the target and its surroundings are minimal, low NETD sensitivity becomes the key factor. A sensor rated below 25 mK, combined with Pulsar’s Image Detail Boost, maintains sharp contrast and clear outlines even when visibility drops.
The Pulsar Merger LRF XP50, with its <25 mK NETD rating and dual-eye design, provides stable, fatigue-free observation and reliable performance in poor weather.
Quick reference: Best specs by hunting condition
| Terrain / Condition | Best spec combination | Pulsar model example |
| Forest / thick cover | 640×480 @ 12 µm | Axion XG35 |
| Open plains / poor weather | 384×288 @ 17 µm + high sensitivity | Telos XQ35 |
| Fog, rain, dawn | NETD <25 mK + Image Detail Boost | Merger LRF XP50 |
No single specification defines thermal imaging success, each environment highlights different strengths. Pulsar’s sensor diversity ensures that whether you’re stalking through forest paths, glassing open farmland, or hunting in misty valleys, there’s a perfectly tuned model for your style. Here’s Riccardo’s pick:
I need a versatile device because I use the thermal unit in wide and different situations; generally speaking, an HD sensor class brings with it a lot of great other features as a low NETD, a fast lens aperture f1.0, a good compromise between a base magnification and a good field of view, always returning a clear and sharp image.
The XL family is what I need also because I spend tons of time watching, hunting, and controlling wildlife during the night. I need a powerful device which supports me 24/7 not depending on the season, the weather conditions, or the size of the target because a small rabbit at 200 meters in a foggy night represents a completely different situation than a wild boar at 100 meters in a clear night. And I need the same clarity and the same opportunity to cull these so different targets or to evaluate their sex, status or class age.
Conclusion
Thermal image quality is the result of balance: resolution, pixel pitch, and NETD work together to reveal every detail in the field. Understanding how these specifications interact helps hunters look beyond numbers and choose a device that performs in real conditions.
Pulsar builds every thermal optic around this principle of integration, ensuring that from sensor to software, each component contributes to real, visible clarity. Whether you need compact precision in thick cover or high-contrast visibility across open plains, there’s a Pulsar device engineered for your style of hunting.
Find your perfect match: Discover where to buy Pulsar’s full range of thermal monoculars, binoculars, and riflescopes
FAQs
Does higher resolution mean better detection range?
Not always. Higher resolution improves image detail and zoom quality but doesn’t automatically extend detection distance. Detection range depends on several factors, including lens size, pixel pitch, and NETD sensitivity. For example, a 384×288 @ 17 µm sensor with a large objective lens may detect targets farther away than a smaller 640×480 device with a 12 μm pixel pitch.
What is a good NETD value for hunting?
For hunting, a NETD below 40 mK is considered good, while NETD <25 mK delivers premium performance in poor visibility. The lower the NETD, the more sensitive the device is to small temperature differences, which is essential for detecting animals in fog, rain, or cold mornings.
How does weather affect thermal imaging performance?
Weather directly influences thermal contrast. In fog, humidity, or rain, the temperature difference between an animal and its surroundings decreases, making detection harder. Devices with low NETD and advanced processing, such as Pulsar’s Image Detail Boost, maintain strong contrast and reveal details even when visibility drops.
What’s the best way to compare thermal devices before buying?
Focus on real-world performance, comparing:
- Sensor specs (resolution, pixel pitch, NETD)
- Lens quality and detection range
- Image processing features (e.g., Image Detail Boost, Dynamic Contrast Adaptation)
- Ergonomics and display resolution
Field testing or checking footage from real hunts offers the best insight into how each device performs under your conditions.
About the expert
Co-Author:
Andrei Yatskevich
Andrei Yatskevich is the Director of Pulsar Optics PL, one of Pulsar’s key manufacturing facilities. A long-term member of the Pulsar team, he brings extensive experience and leadership in advancing the company’s optical production capabilities.
Expert Contributor:
Riccardo Tamburini
Riccardo Tamburini is a lifelong outdoorsman, hunter, fisherman, and professional wildlife photographer and filmmaker.
With over 35 years of experience across plains and mountains in Italy and abroad, he combines field expertise with a mechanical engineering background to explain the technology behind rifles, optics, and digital devices.
Before purchasing any night or thermal vision device, please make sure you adhere to the local legislation and only use it when it is allowed. Our ambassadors come from various countries and travel a lot, which allows them to test different devices. We do not encourage or support the illegal use of our devices in any events. If you wish to learn more about export and sales restriction policy, please visit the following link: Export and Sales Restriction Policy.