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Tektronix provides test and measurement instruments, solutions and services for the computer, semiconductor, military/aerospace, consumer electronics and education industries worldwide.
A matrix, block or single pel representing a monochrome representation of the signal and related to the primary colours in the manner defined in the bit stream. The symbol used for luminance is Y.
Industry:Software
An adjustment used in the electrical measurement of television signal noise values, to take into account the difference between the observable effect of noise in a television picture and the actual electrical value of noise.
Industry:Software
The act of storing switcher control panel data into memory in a real-time mode (learning as they happen).
Industry:Software
A test signal with five steps of luminance change, each step having a constant frequency and phase chrominance signal. This signal is used to test for Differential Phase distortions.
There is also a 10 step version of this signal.
Industry:Software
Circuit that connects signals from external devices as inputs to the microprocessor system.
Industry:Software
Video originates with linear-light (tristimulus) RGB primary components, conventionally contained in the range 0 (black) to +1 (white). From the RGB triple, three gamma-corrected primary signals are computed; each is essentially the 0.45-power of the corresponding tristimulus value, similar to a square-root function. In a practical system such as a television camera, however, in order to minimise noise in the dark regions of the picture it is necessary to limit the slope (gain) of the curve near black. It is now standard to limit gain to 4.5 below a tristimulus value of +0.018, and to stretch the remainder of the curve to place the Y-intercept at –0.099 in order to maintain function and tangent continuity at the breakpoint:
#Rgamma = 1.099 * pow (R,0.45) - 0.099
#0.099 Ggamma = 1.099 * pow (G,0.45) - 0.099
#0.099 Bgamma = 1.099 * pow (B,0.45) - 0.099
Luma is then computed as a weighted sum of the gamma-corrected primaries:
#Y = 0.299 * Rgamma + 0.587 * Ggamma + 0.114 * Bgamma
The three coefficients in this equation correspond to the sensitivity of human vision to each of the RGB primaries standardised for video. For example, the low value of the blue coefficient is a consequence of saturated blue colours being perceived as having low brightness. The luma coefficients are also a function of the white point (or chromaticity of reference white). Computer users commonly have a white point with a colour temperature in the range of 9300 K, which contains twice as much blue as the daylight reference CIE D65 used in television. This is reflected in pictures and monitors that look too blue. Although television primaries have changed over the years since the adoption of the NTSC standard in 1953, the coefficients of the luma equation for 525- and 625-line video have remained unchanged. For HDTV, the primaries are different and the luma coefficients have been standardised with somewhat different values. The signal which represents brightness, or the amount of light in the picture.
This is the only signal required for black and white pictures; for colour systems it is obtained as the weighted sum (Y = 0.3R + 0.59G + 0.11B) of the R, G, and B signals.
Luminance Factor – At a surface element of a nonself-radiating medium, in a given direction, under specified conditions of illumination, ratio of the luminance of the surface element in the given direction to that of a perfect reflecting or transmitting diffuser identically illuminated. No “perfect reflectors” exist, but properly prepared magnesium oxide has a luminance factor equal to 98% and this is usually employed to define the scale.
Industry:Software
Unwanted electrical signals produced by electronic equipment or by magnetic tape. Mostly confined to the extremes of the audible frequency spectrum where it occurs as hum and/or hiss. A-weighted noise is noise measured within the audio frequency band using a measuring instrument that has a frequency selective characteristic. The frequency sensitivity of the measuring instrument is adjusted to correspond to that of the average human hearing response.
Industry:Software
An algebraic metaphor for the amount of time a learner needs to learn a new task (such as operating an item of television production equipment).
Industry:Software
A test signal which consists of three chrominance packets with the same phase, on the same luminance level (50 IRE), with different amplitudes (20, 40, and 80 IRE). This signal is used to test for chrominance nonlinear phase distortion and chrominance to luminance intermodulation distortion.
Industry:Software
A) Typically refers to sending information or data signals to and from devices. b) Lines or devices used to transfer information outside the system.
Industry:Software
