Glossary

Drift

Slow, global displacement of the field of view over time (microscope, sample, mechanical/thermal stability), measurable in \((x, y)\) and sometimes in \(z\).

Drift correction

Estimation and compensation of drift in order to align localizations (or images) within a stable reference frame.

Gaussian fitting

Fitting a (2D/3D) Gaussian to a PSF to estimate parameters (position, amplitude, background, width, etc.).

High-resolution image

Image reconstructed from a set of localizations (point cloud) by applying a rendering method (binning, Gaussian rendering, histogram, etc.).

Localization

Estimation of the position \((x, y)\) (and possibly \(z\)) of a single molecule from its image (PSF), typically by fitting a model or an experimental PSF.

Pipeline

Reproducible sequence of processing steps (pre-processing, localization, filtering, tracking, rendering, export), with saved parameters.

PSF (Point Spread Function)

Optical impulse response of the microscope. It describes the image formed by a point source and determines localization precision.

ROI (Region Of Interest)

Sub-region of an image extracted around an area of interest (e.g., around a local maximum) to perform local processing (thresholding, fitting, etc.).

SNR (Signal-to-Noise Ratio)

Signal-to-noise ratio, an indicator of the quality of a measured signal. A low SNR degrades localization precision and increases the risk of false positives.

Threshold

Limit value used to separate a signal (pixels/objects) from the background. It can be fixed, automatic, or depend on a noise model.

Tracking

Association of localizations belonging to the same molecule across frames in order to form a trajectory (track).

Watershed

Segmentation method based on an image’s topography (“watershed” analogy), often used to separate nearby objects.