Glossary

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Quantization

The fact that some digital numbers can only take a set of discrete values.

RAW

Image format as output by a sensor

RAW converter

Software for transforming sensor image output into an viewable image using, for example, screens and printers.

RBG image

An image whose pixels contain values corresponding to Red, Green and Blue channels

Reflectance

The property of light reflection on a material (quantity, direction, spectrum…).

Reflection spectra

The data giving for each wavelength the ratio between the reflected light and the incident light

Repeatability

The fact that a measurement performed in the same conditions will always produce the same results. It is a necessary condition for measurement accuracy although not sufficient.

Reportage (use case)

Reportage includes all forms of photography that tell a story related to people’s lives. Wedding photography, photojournalism, street photography, documentary and war photography all fall into this category. Read more about lens Reportage Score requirements.

Resolution

Resolution of a camera describes its ability to resolve fine details. Both the lens and the sensor have an impact on resolution. Read more about how resolution is defined, measured and scored.

RGB

From Red, Green, Blue, the typical primaries used in color space, image synthesis or image capture.

Sampling

The process of capturing a finite number of values from an infinity of values.

Saturation (sensor)

The highest attainable gray level on a sensor.

Scaling, up and down, bi-cubic

Changing the resolution of an image. Scaling up means increasing the resolution, and scaling down means decreasing. A bi-cubic algorithm can be used to obtain a softer result, by intelligently merging the values of neighboring pixels.

Score or DxOMark Score

DxOMark Score (“Score” for short) is a numerical value or, graphically, a number of stars that reports the lens or camera sensor performance for a given Use Case or Metric. Read more about Sensor Scores, and Lens Scores.

Sensitivity

See ISO speed.

Sensor

A device that transforms light into a digital signal.

Sensor integration time

Sensor Overall Score (A DxOMark Score for sensor)

The Sensor Overall Score is an average of the Portrait Score based on Color Depth, the Landscape Score based on Dynamic Range and the Sports Score based on Low-Light ISO. It shows only sensor performance. Read more about Sensor Overall Score.

Sensor Scores (DxOMark)

DxOMark reports four sensor performance scores.

Three for typical Use Cases: PortraitLandscape and Sports.

One global score, the Sensor Overall Score, to report on the performance for a general purpose use case.

Read more about DxOMark Sensor Scores.

Sensor spectral sensitivity

Characteristic of a sensor that describes its response to light with known wavelength.

Sensor Use Case Scores

DxOMark reports sensor performance Scores for three typical Use Cases: Portrait, Landscape and Sports. A global score the Sensor Overall Score reports on the performance for a general purpose use case. Read more about DxOMark Sensor Scores.

Shadows

Exposure levels corresponding to low gray levels on the sensor.

Sharpness

Sharpness is a subjective quality attribute of an image or a lens. Sharpness indicates the visually perceived quality of details of an image or details reproduced by a lens. It is associated with both resolution and contrast of reproduced details (within an image or by a lens).

The DxOMark score for Sharpness is based on the Perceptual Megapixel (P-Mpix) concept that weights the Modulation Transfer Function (MTF) of the lens with the human visual acuity. Read more about Perceptual Megapixels.

Shutter speed

Device or process allowing to start and stop light acquisition on a sensor.

Shutter, electronic rolling

Process that allows exposing the lines of the sensor one after the other.

Shutter, mechanical

Mechanical device used to block light from or allow light onto a sensor.

Signal-to-noise ratio (SNR)

Ratio between the value of a signal and the noise standard deviation.

SNR curve

The data showing the signal-to-noise ratio function of the gray level values.

Spectral sensitivity

The data describing the relative amount of light converted into signal for each wavelength

Spectrometer

Device used to measure the variation of the energy of incident light as a function of wavelength.

Spectrum

The data relating any arbitrary wavelength to a numerical value.

Sports & Wildlife (use case)

Sports & Wildlife photography typically involves shooting moving people or animals at a distance, and generally requires fast (at least f/4) and long or very long telephoto lenses (at least 120 mm).Read more about Lens Use Cases and Sensor Use Cases definitions.

Standard deviation

The expected difference of a signal to its mean value.

Structures, maze

Sub-sampling

The process of decreasing the number of pixels of a digital signal. It is commonly used to display an image on a lower resolution device (screen or print).

Target exposure

A gray level value representing the expected gray level over all possible well exposed photos.

Thermal noise

Tonal range

Tonal range is the effective number of distinguishable gray levels a camera can produce.

Transmission chart, target

Target illuminated from behind. Light beams go through the target to reach the camera.

Transmission or Light Transmission

Transmission of a photographic lens describes its ability to transmit light from the photographic scene to the sensor surface. Lenses consists of many glass elements, each reflecting or absorbing a portion of the light; therefore the more elements, the lower the transmission. Read more about how transmission is defined, measured and scored.

Travel & Family (use case)

Travel & Family photography involves shooting both indoors and out, and includes landscapes, portraits, group shots, and close-ups when sightseeing. The field of view requirement is very broad, from wide-angle to long telephoto, so photographers typically look for a high-power zoom with a good trade-off between all image quality parameters. Read more about lens Travel Score requirements.