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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.
The standard vector-based structure of the Windows operating system. Bitmapped images may be embedded in WMF files.
Industry:Software
A standard networking protocol suite approved by the CCITT and ISO. This protocol suite defines standard physical, link, and networking layers (OSI layers 1 through 3). X.25 networks are in use throughout the world.
Industry:Software
The set of CCITT communications standards covering mail services provided by data networks.
Industry:Software
The horizontal axis of a graph. When a television signal is examined in one dimension, the x-axis is usually time. When it is examined in three dimensions, the x-axis is usually horizontal resolution.
Industry:Software
a) An abbreviation or symbol for luminance, the black and white information in a television signal. b) Signal which is made up of 0.59G + 0.3R + 0.11B. c) The y-axis of the chart of the spectral sensitivity of the human visual system.
Industry:Software
A generalized set of CAV signals: Y is the luminance signal, C1 is the 1st color-difference signal, and C2 is the 2nd color-difference signal.
Industry:Software
The international standard ITU-R BT.601-1 specifies eight-bit digital coding for component video, with black at luma code 16 and white at luma code 235, and chroma in 8-bit two’s complement form centered on 128 with a peak at code 224. This coding has a slightly smaller excursion for luma than for chroma: luma has 219 risers compared to 224 for Cb and Cr. The notation CbCr distinguishes this set from PbPr where the luma and chroma excursions are identical. For Rec. 601-1, coding is eight bits per component.
: Y_8b = 16 + 219 * 9
: Cb_8b = 128 + 112 * (0.5/0.866) * (Bgamma - Y)
: Cr_8b = 128 + 112 * (0.5/0.701) * (Rgamma - Y)
Some computer applications place black at luma code 0 and white at luma code 255. In this case, the scaling and offsets above can be changed accordingly, although broadcast-quality video requires the accommodation for headroom and footroom provided in the CCIR-601-1 equations. ITU-R BT.601-1 Rec. calls for two-to-one horizontal subsampling of Cb and Cr, to achieve 2/3 the data rate of RGB with virtually no perceptible penalty. This is denoted 4:2:2. A few digital video systems have used horizontal subsampling by a factor of four, denoted 4:1:1. JPEG and MPEG normally subsample Cb and Cr two-to-one horizontally and also two-to-one vertically, to get 1/2 the data rate of RGB. No standard nomenclature has been adopted to describe vertical subsampling. To get good results using subsampling you should not just drop and replicate pixels, but implement proper decimation and interpolation filters. YCbCr coding is employed by D1 component digital video equipment.
Industry:Software
The three nonlinear video signals in which the information has been transformed into a luminance signal and two chrominance signals, each of which has been subject to nonlinear processing, and the chrominance signals at least have also been bandlimited. By convention, C'R, and C'B represent color-difference signals in digital format with typical excursion of values for 16 to 240.
Industry:Software
The human visual system has less spatial acuity for magentagreen transitions than it does for red-cyan. Thus, if signals I and Q are formed from a 123 degree rotation of U and V respectively, the Q signal can be more severely filtered than I (to about 600 kHz, compared to about 1.3 MHz) without being perceptible to a viewer at typical TV viewing distance.
YIQ is equivalent to YUV with a 33 degree rotation and an axis flip in the UV plane. The first edition of W.K. Pratt “Digital Image Processing,” and presumably other authors that follow that bible, has a matrix that erroneously omits the axis flip; the second edition corrects the error. Since an analog NTSC decoder has no way of knowing whether the encoder was encoding YUV or YIQ, it cannot detect whether the encoder was running at 0 degree or 33 degree phase. In analog usage, the terms YUV and YIQ are often used somewhat interchangeably. YIQ was important in the early days of NTSC, but most broadcasting equipment now encodes equiband U and V.
The D2 composite digital DVTR (and the associated interface standard) conveys NTSC modulated on the YIQ axes in the 525-line version and PAL modulated on the YUV axes in the 625-line version. The set of CAV signals specified for the NTSC system: Y is the luminance signal, I is the 1st colordifference signal and Q is the 2nd color-difference signal.
Industry:Software
