EMVA 1288 Characterization

Prerequisites

Quantum Efficiency -> Noise, SNR, and Dynamic Range -> this page.

The EMVA 1288 standard (European Machine Vision Association, currently Release 4.0) defines a unified methodology for measuring and reporting image sensor performance. This page summarizes its parameter set and how each item maps to the noise and signal model used elsewhere in this chapter.

EMVA 1288 is structured around a small set of physical inputs and a parameter list that downstream measurements report. The simplification it makes is a linear model: signal is proportional to incident photon number, and noise sources are independent and add in quadrature.

Parameter set

Sensitivity metrics

Parameter	Symbol	Meaning
Quantum efficiency	$\eta (\lambda )$	Probability that an incident photon at $\lambda$ produces a collected electron
Responsivity	$R$	Slope of the photon-transfer line in DN per photon
Absolute sensitivity threshold	${\mu }_p^{\text{min}}$	Photon count at which SNR = 1

The sensitivity threshold is the minimum detectable photon number per pixel and is approximately

$${\mu }_p^{\text{min}}\approx \frac{1}{\eta }({\sigma }_{\text{read}}+\sqrt{{\sigma }_{\text{read}}^2+\frac{1}{4}})$$

with ${\sigma }_{\text{read}}$ in electrons.

Noise metrics

Parameter	Symbol	Meaning
Temporal dark noise	${\sigma }_d$	Read-noise floor in $e^{-}$ RMS at zero exposure
PRNU	$u_{\text{PRNU}}$	Pixel-to-pixel gain non-uniformity (fraction of signal)
Saturation SNR	${\text{SNR}}_{\text{max}}$	Best achievable SNR before saturation

In the shot-noise-limited regime, ${\text{SNR}}_{\text{max}}\approx \sqrt{{\mu }_{\text{sat}}}$ where ${\mu }_{\text{sat}}$ is the saturation signal in electrons.

Capacity metrics

Parameter	Symbol	Meaning
Saturation capacity	${\mu }_{\text{sat}}$	Maximum signal in $e^{-}$ (full well)
Dynamic range	DR	Ratio of ${\mu }_{\text{sat}}$ to noise floor
Useful bits	$b_{\text{useful}}$	Effective ADC resolution given noise

The useful bits are computed from $\text{DR}$ as $b_{\text{useful}}={\log }_2({\text{DR}}_{\text{linear}})$ and may be lower than the ADC's nominal bit depth when read noise exceeds 1 DN.

Dark current metrics

Parameter	Symbol	Meaning
Mean dark signal rate	${\mu }_I$	Dark current in $e^{-}/\text{s}$ at nominal $T$
Dark current doubling temperature	$T_d$	$\mathrm{\Delta }T$ that doubles ${\mu }_I$, typically 6–8 °C
DSNU	${\sigma }_y^{\text{dark}}$	Spatial standard deviation of dark signal

The dark signal model is ${\mu }_{\text{dark}}(T,t)={\mu }_I(T)t$. Combined with the Arrhenius dependence from Noise, SNR, and Dynamic Range, this lets the standard report dark current at any operating temperature from a single calibration.

SNR curve and grade reporting

EMVA 1288 expects the SNR-versus-irradiance curve to be reported with:

• The actual measured curve (limited by read noise at low end, shot noise in the middle, PRNU at the top)
• The ideal shot-noise-limited reference ${\text{SNR}}_{\text{ideal}}=\sqrt{N}$

The gap between the two curves quantifies how far the sensor deviates from ideal photon counting and is the most informative summary plot in the standard.

A typical EMVA 1288 report tags each parameter with a quality grade — for example:

• Excellent — best-in-class performance for that metric
• Typical — common production range
• Below typical — may limit specific applications

The grading is not part of the linear model itself; it is a convention for quickly flagging which parameter is the bottleneck for a given imaging task.

Boundary with adjacent pages

Adjacent page	Difference
Noise, SNR, and Dynamic Range	Defines the underlying noise model used by EMVA 1288. Read it first if you are not already familiar with PRNU/DSNU, FWC, and the PTC.
Quantum Efficiency	EMVA 1288 reports a single integrated $\eta$ per spectral band; this page covers the spectrally and spatially resolved definition.
Signal Chain	The signal-chain page converts QE into camera-system signal predictions; EMVA 1288 instead reports sensor-only metrics at fixed irradiance.

Browser simulator

• EMVA 1288 Dashboard — explore the full parameter set interactively, with the actual-vs-ideal SNR curve and quality grades.