Definition

Fixed-Pattern Noise (FPN) is a sensor-related noise artifact where certain pixels consistently produce higher or lower signal values than others under identical conditions. Unlike random noise, Fixed-Pattern Noise remains spatially fixed in the same pixel locations, appearing as stripes, grids, blotches, or repeating textures in drone imagery.

Usage

In drone operations, Fixed-Pattern Noise appears most often in thermal, multispectral, hyperspectral, and low-light RGB sensors. It becomes noticeable during uniform scenes such as skies, smooth rooftops, water surfaces, or flat agricultural fields. Fixed-Pattern Noise directly affects image clarity, temperature accuracy, and data reliability in mapping, inspections, and analytics.

Relevance to the Industry

Fixed-Pattern Noise is a critical limitation in professional drone imaging because it can:

• Distort thermal measurement accuracy
• Create misleading hot or cold artifacts
• Degrade multispectral and hyperspectral data quality
• Reduce the effectiveness of automated inspection algorithms
• Lower confidence in scientific and industrial analysis

As drone sensors become more sensitive and are used for automated diagnostics, controlling Fixed-Pattern Noise is essential for ensuring trustworthy data outputs.

How Does FPN (Fixed-Pattern Noise) Work?

Fixed-Pattern Noise occurs due to slight manufacturing variations in pixel electronics within a sensor array. Each pixel responds slightly differently to the same input signal. Because these variations stay consistent over time, the noise pattern remains “fixed” in the same locations.
There are two primary forms:

• Offset FPN: Differences in baseline signal between pixels
• Gain FPN: Differences in how strongly pixels amplify incoming signal

Drone imaging systems reduce Fixed-Pattern Noise using Flat-Field Correction (FFC), dark-frame subtraction, and digital calibration algorithms that normalize pixel response before images are recorded.

Example in Use

A thermal drone scans a large warehouse roof at night. Without correction, faint vertical banding appears across the thermal image due to sensor Fixed-Pattern Noise. After FFC calibration, the banding disappears, allowing the operator to clearly identify real heat loss and insulation faults.

Frequently Asked Questions About FPN (Fixed-Pattern Noise)

Is FPN the same as random noise?
No. Random noise changes from frame to frame, while Fixed-Pattern Noise stays locked to the same pixel locations every time.

Is FPN more common in thermal cameras?
Yes. Thermal sensors are especially susceptible to Fixed-Pattern Noise due to detector temperature sensitivity and manufacturing tolerances.

Can FPN be completely eliminated?
It can be greatly reduced through FFC calibration and advanced processing, but it cannot be fully eliminated at the hardware level.