Machine Vision Knowledge & Calculators

Accuracy

How close a measurement is to the true value; verified with certified references.

Anomaly detection

Deep-learning method trained mainly on good parts that flags anything that looks different.

Area-scan camera

Camera that captures a full 2D image in one exposure.

Backlight

Light placed behind the part so it appears as a dark silhouette.

Bandpass filter

Lens filter that passes only a narrow wavelength band, blocking ambient light.

Bayer filter

Color filter mosaic on color sensors; colors are interpolated, reducing effective resolution.

Bit depth

Number of gray levels per pixel (8 bit = 256, 12 bit = 4096).

Blob analysis

Tool that finds and measures connected regions of similar pixels.

Bright field

Lighting where specular reflection from flat areas enters the lens, making them bright.

Calibration

Relating pixels to real-world units and coordinates, and correcting lens distortion.

Caliper / edge tool

Tool that finds edge positions along a line, often with sub-pixel precision.

CoaXPress

High-bandwidth camera interface over coaxial cable, used with frame grabbers.

Coaxial illumination

Light sent along the camera axis via a beam splitter; flat reflective surfaces appear bright.

Collimated light

Light with parallel rays, used for precise silhouettes and with telecentric lenses.

Dark field

Low-angle lighting where flat areas stay dark and edges or defects scatter light into the lens.

Deep learning

Neural-network methods that learn to classify, detect or segment from labeled images.

Depth of field (DOF)

Distance range in front of and behind the focus plane that appears acceptably sharp.

Diffuse lighting

Light arriving from many directions (dome, flat dome) to suppress glare and texture.

Distortion

Geometric deviation of the image from the object, usually given in percent.

DPM (direct part mark)

Code marked directly on a part by dot-peen, laser or ink-jet.

Dynamic range

Ratio between the brightest and darkest signal a camera can capture.

Encoder

Sensor that reports motion; used to trigger cameras at constant spacing.

Exposure time

Time the sensor collects light for one image.

F-number (f/N)

Ratio of focal length to aperture diameter; higher numbers mean smaller apertures.

Field of view (FOV)

Area on the object captured by the camera.

Focal length

Optical property of a lens that, with the sensor size, sets the field of view.

Frame grabber

PCIe card that acquires images from high-bandwidth cameras.

Gain

Electronic amplification of the image signal; increases noise.

Gauge R&R

Study of how much of the tolerance is consumed by measurement variation.

GenICam

Generic standard for camera control, enabling software to work with many cameras.

GigE Vision

Camera interface standard over Gigabit Ethernet, up to 100 m cables.

Global shutter

Sensor that exposes all pixels at the same time — no distortion of moving parts.

Image circle

Diameter of the sharp image a lens projects; must cover the sensor diagonal.

Jumbo frames

Large Ethernet packets that reduce CPU load for GigE cameras.

Laser triangulation

3D principle measuring height from the shift of a laser line seen at an angle.

Line-scan camera

Camera with one or a few pixel lines that builds images as the object moves.

Lens mount

Mechanical interface between lens and camera (C, CS, M42, F, …).

lp/mm

Line pairs per millimetre — a measure of lens resolution.

Magnification

Ratio between image size on the sensor and object size.

Minimum object distance (MOD)

Closest distance at which a lens can focus.

Module (code)

Smallest bar or square of a barcode or 2D code.

Nyquist frequency

Highest spatial frequency a sensor can sample: 1 line pair per 2 pixels.

OCR / OCV

Optical character recognition (reading text) / verification (checking expected text).

Overdrive

Driving LEDs above continuous current for very short, bright pulses.

Pattern matching

Tool that finds a trained pattern's position and orientation in an image.

Pixel size

Physical size of one sensor pixel, e.g. 3.45 µm.

Point cloud

Set of 3D points representing a surface.

PoE

Power over Ethernet — power and data on one cable.

Polarizer

Filter that passes light of one polarization; reduces glare.

Quantum efficiency

Share of photons converted into signal at a given wavelength.

Quiet zone

Empty margin required around a code for reliable decoding.

Repeatability

Spread of repeated measurements of the same object.

Resolution

Number of pixels of a sensor, or the smallest detail a system can resolve.

Rolling shutter

Sensor that exposes rows one after another; skews fast motion.

ROI (region of interest)

Part of the image that is read out or processed, increasing speed.

Strobe

Light switched on only during exposure.

Structured light

3D method projecting patterns and measuring their deformation.

Sub-pixel

Edge or position calculated finer than one pixel from gray-level transitions.

SWIR

Short-wave infrared (about 900–1700 nm); sees moisture and through silicon.

TDI

Time delay integration — line-scan technique adding signal over several lines for sensitivity.

Telecentric lens

Lens with constant magnification over a depth range; used for measurement.

Time-of-flight (ToF)

3D method measuring the travel time of light to each pixel.

USB3 Vision

Camera interface standard over USB 3, for short cable distances.

Working distance (WD)

Distance from the front of the lens to the object.

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