Glossary: S
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- Sample (signal)
- The measured value of a signal at a single point in time or space.…
- Sampling frequency (signal)
- The frequency that a signal is sampled along an axis of time or space.…
- See Also Sampling rate (audio); Sampling rate (image)
- Sampling rate (audio)
- Sampling rate or sampling frequency defines the number of samples per second (or per other unit) taken from a continuous signal to make a discrete or digital signal. For time-domain signals like the waveforms for sound (and other audio-visual content types), frequencies are measured in in hertz (Hz) or cycles per second. The Nyquist–Shannon sampling…
- Sampling rate (image)
- The spatial frequency of the digital sampling. The reciprocal of the center-to-center distance between adjacent pixels.…
- Saturation
- The attribute of color that expresses the degree of departure from a gray of the same lightness. When a color has no saturation, it is a shade of gray. Saturation describes the purity of a color, and along with hue and brightness is among the three attributes that specify a color.…
- Scene-referred
- See Image state
- Scotopic sensitivity
- Scotopic sensitivity refers to visual sensitivity under conditions of low light, where radiant energy stimulates the rods (retinal photo-receptors that are achromatic, containing only one type of pigment). Scotopic vision does not involve the perception of color.…
- See Also Photopic sensitivity; Mesopic sensitivity
- Sensitivity
- The reciprocal of the amount of light necessary to achieve a desired output response.…
- Sensor
- Device that converts optical image into an electronic signal. Sensors detect and convey information used to create digital images, video, audio, and more. In digital imaging, the sensor allows the camera to convert photons (light) into electrical signals and data that can be interpreted by the capture device to create a digital representation of an…
- See Exposure
- Sensor array
- See Array
- Service file
- See Derivative file
- SFR
- Spatial Frequency Response (SFR) describes an imaging system\'s ability to maintain the relative contrast of input stimuli.…
- See Modulation transfer function
- Sharpening
- Amplification of the SFR by means of image processing to achieve sharper appearing images. Also, a class of image processing operations that enhances the contrast of selective spatial frequencies, usually visually important ones.…
- Sharpness
- The visually perceived quality of being crisp or of containing detail.…
- Sheetfed scanner
- A sheetfed scanner (also referred to as an automatic document scanner or ADF scanner) is a digital imaging system specifically designed for scanning loose sheets of paper, widely used by businesses to scan office documents and less frequently used by archives and libraries to scan books that have been disbound or other robust unbound documents.…
- See Also Automatic document feeder; Duplex scanner
- Sidecar file
- See XMP sidecar file
- Sidecar metadata
- See XMP sidecar file
- Signal-to-noise ratio
- Abbreviated as SNR, it is a measure of the relative power of a desired or ideal signal to the power of an undesired signal or noise. SNR is typically measured in decibels.…
- See Also Decibel; Peak signal-to-noise ratio
- Skew
- The angle of deviation in a digital image from the paper edge, text lines or other visual reference elements. Skew is expressed numerically as the tangent of the deviation angle in degrees, either clockwise or counterclockwise. It applies to the angle of two-dimensional image orientation. Skew is a common occurance in automatic…
- Slant edge target
- An imaging performance target used to measure the SFR and resolution of an image capture device using edge gradient analysis.…
- SNR
- See Signal-to-noise ratio
- Sound field
- Indicates the aural space arrangement of a mono, stereo, or multichannel sound recording, e.g., monaural, stereo, joint stereo, surround sound 5.1, etc. The term generally is used in a playback context, where a set of loudspeakers have been set up, e.g., for a surround sound presentation in a theater. The term may be compared to…
- See Also Multichannel (audio); Channel (audio); Track (audio)
- Source metadata
- See Metadata source
- Spatial frequency
- The reciprocal of the distance between any two cyclical spatial features.…
- Spatial frequency response
- See SFR
- Spatial resolution
- See Resolution
- SPC
- See Statistical Process Control
- SPD
- See Spectral Power Distribution
- Spectral Power Distribution
- Spectral Power Distribution (SPD) curves chart the spectral characteristics of a light source, showing the radiant power of the light source at each wavelength or band of wavelengths across the visible spectrum.…
- Spectrodensitometer
- A densitometer that makes use of spectral data, providing densitometric readings at discrete spectral intervals.…
- See Densitometer
- Spectroradiometer
- A spectroradiometer is an instrument designed to measure the spectral power distributions of illuminants, measuring the radiant power from a light source as a function of wavelength.…
- Specular reflection
- See Reflection specular
- sRGB
- Standard RGB color space created by HP and Microsoft for use on monitors, printers, and the Internet. sRGB uses the ITU-R BT.709-5 primaries that are also used in studio monitors and HDTV, and a transfer function (gamma correction) typical of CRTs, all of which permits sRGB to be directly displayed on typical monitors. The sRGB…
- See Also Color model; Gamma correction
- Stacking
- See Focus Stacking
- Standard illuminant
- A standard illuminant is a published spectral profile of visible light. The most commonly used and referred to standard illuminants are published by the CIE. A CIE illuminant is a spectral characterization or model that defines the amount of energy at each wavelength across the spectrum. Physical light sources listed as…
- See CIE
- Statistical Process Control
- Statistical Process Control (SPC) is a method of monitoring and controlling processes through statistical analysis. The basic components of SPC include measuring and monitoring the processes, eliminating variances to maximize consistency, and improving the process to meet or exceed requirements or specifications. Control charts are a common tool in SPC and are used to…
- Stitching
- An image processing method combining multiple overlapping images to create a single image. Stitching can be used in scanning where a single scan of a large object is not able to produce sufficiently high resolution. Accurate digital alignment to create a visually seamless and uniform image from the individual component images is technically complex and…
- Storage Aspect Ratio (SAR)
- SAR (Storage Aspect Ratio) is the width and height of a video frame expressed as a ratio. For example, a video frame with a width of 720 pixels and height of 480 pixels (720x480) would have a SAR of 3:2.
SAR can be calculated with the following equation: SAR = DAR / PAR
Note that some…
- See Also Pixel Aspect Ratio (PAR); Display Aspect Ratio (DAR); Aspect ratio
- Structural metadata
- See Metadata structural
- Structured audio
- Dynamically constructed sound resulting from the processing of data through combinations of software and hardware. Such software includes sequencers and trackers that use data to control when individual sound elements should start and stop, to set values for attributes such as volume and pitch, and for other effects that should be applied to the…
- See Waveform (sound)
- Subtitles
- Timed text of video dialog that is usually written in a language other than the language of the sound essence. Subtitles are designed for hearing viewers who do not understand the language being spoken in the video and do not indicate audio information important to understanding the program. Subtitles rarely identify speakers or nonverbal sounds…
- See Also Open captions; Closed captions