Sensors & Digital Capture — 60 Terms Defined

Aliasing Sensors & Digital Capture The misrepresentation of detail finer than a sampling system can resolve, appearing as false structure rather than as blur.

Amp Glow Sensors & Digital Capture A coloured brightening at one edge or corner of a long exposure, caused by heat and stray light from on-chip electronics.

Analogue Gain Sensors & Digital Capture dB or × Amplification applied to the sensor's signal before it is digitised, which is the physical mechanism behind ISO settings.

Analogue-to-digital Converter Sensors & Digital Capture bits The circuit that turns the analogue voltage from each photosite into a discrete numerical value.

Backside-illuminated Sensor Sensors & Digital Capture A sensor design in which the wiring layer is moved behind the photodiodes so light reaches them unobstructed.

Banding Noise Sensors & Digital Capture Horizontal or vertical stripes appearing in heavily lifted shadows, caused by variations between readout channels.

Bayer Filter Sensors & Digital Capture The dominant colour filter array pattern, using two green filters for every red and blue in a repeating square of four. RGGB in 2×2 blocks

Black Level Sensors & Digital Capture ADU The numerical value a sensor reports for a completely unexposed photosite, subtracted during processing to establish true black.

Blooming Sensors & Digital Capture The spilling of charge from a saturated photosite into its neighbours, spreading a bright highlight beyond its true boundaries.

CCD Sensor Sensors & Digital Capture A sensor type in which charge is shifted across the chip to a single output amplifier for conversion.

CMOS Sensor Sensors & Digital Capture A sensor type in which each photosite has its own amplifier and the charge is converted to voltage at the pixel itself.

Colour Filter Array Sensors & Digital Capture A mosaic of coloured filters over the photosites that allows a monochrome sensor to record colour.

Dark Current Sensors & Digital Capture e⁻/s Charge that accumulates in a photosite from thermal energy rather than from light, growing with exposure time and temperature.

Dark Frame Sensors & Digital Capture An exposure made with the shutter closed, at the same duration, temperature and ISO as the real image, used to characterise sensor noise.

Dead Pixel Sensors & Digital Capture count A photosite that records no signal at all, appearing as a permanently black point in every image.

Demosaicing Sensors & Digital Capture The process of reconstructing a full-colour image from the single-colour samples recorded under a colour filter array.

Dual Conversion Gain Sensors & Digital Capture A sensor design offering two selectable amplification circuits, one optimised for dynamic range and one for low noise at high ISO.

Effective Pixels Sensors & Digital Capture MP The number of photosites actually contributing to the final image, as distinct from the total on the chip.

False Colour Sensors & Digital Capture Coloured artefacts appearing on fine detail, caused by the colour filter array sampling different colours at different positions.

Fixed Pattern Noise Sensors & Digital Capture Noise that appears in the same places on every frame, caused by small manufacturing differences between photosites.

Flat Field Correction Sensors & Digital Capture Dividing an image by a frame of evenly illuminated field to remove vignetting, dust shadows and photosite sensitivity variation. Corrected = (light − dark) / (flat − bias)

Foveon Sensor Sensors & Digital Capture A sensor that records all three colours at every location by stacking three photodiode layers at different depths in the silicon.

Full-well Capacity Sensors & Digital Capture e⁻ (electrons) The maximum number of electrons a photosite can hold before it saturates and stops responding to further light.

High ISO Noise Reduction Sensors & Digital Capture levels In-camera processing that smooths noise in high-sensitivity images before writing the JPEG.