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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 CLUT is a compression scheme where pixel values in the bitmap represent an index into a colour table where the table colours have more bits-per-pixel than the pixel values. In a system where each pixel value is eight bits, there are 256 possible values in the lookup table. This may seem a constraint but, since multiple lookup tables can be referenced, there can be many tables with varying 256 colour schemes. CLUTs work best for graphics where colours do not have to be natural.
Industry:Entertainment
The luminance level in a projected image that is correlated with subjective scene black has two sources: in photographic and other light-modulating systems there will be luminance from whatever transmitted light passes through the maximum modulating density representing scene black, additional luminance may be produced by nominateforming light (flare, room illumination, stray light, etc.).
Industry:Entertainment
A colour map is just a numbered list of colors. Each colour is specified in terms of its red, green, and blue components.
Industry:Entertainment
The luminance level which produces the perception of black on the monitor display. This subject has not been explored extensively, but Bartleson and Novick present evidence that it is relative to the high-light or white level, such that the luminance ratio to produce subjective black on a monitor is higher than that in a televised scene. They propose a luminance ratio of 100:1 for subjective white to black on TV monitors in a control room “dimly lighted.” This luminance ratio specification has been formalised in SMPTE RP 166.
Industry:Entertainment
In normal animation, the images representing separate frames are written on separate pieces of artwork. In computer colour map animation, many images can be written into a frame buffer, each with a different colour number. By “cycling” white, for example, through the colour map, so that only one image at a time is visible, the illusion of animation can be achieved very quickly. PictureMaker’s wireframe test mode works this way.
Industry:Entertainment
That fraction of the high-light luminance required in a scene reproduced on a television display to convey the perception of black. The luminance of subjective black on a CRT has been studied by Lowry and Jarvis, who measured luminances on the original scenes, and compared the subjective appearance on a CRT display, as evaluated by viewing audiences. They found that the perception of black depends on a great many factors both in the reproduced scene and in the viewing conditions such as average scene reflection, luminance of areas adjacent to the display, etc. In most situation, luminance levels of 1/40 to 1/60 of the highlight luminance produce the perception of black even though the scene luminance range may reach 200:1 or more. It follows, then, that a scene element that is perceived as black may not necessarily be at reference-black level in a video signal.
Industry:Entertainment
Colour mapping is distinguished by the following: a) Each pixel contains a colour number (or address) referring to a position in a colour map. Each pixel has “n” bits, so there are “2 to the n” colour map addresses.
b) A hardware device called the colour map defines the actual RGB values for each color.
Industry:Entertainment
The amplitude region of the composite video signal below reference-black level in the direction of the synchronising pulses.
Industry:Entertainment
A method of correcting colour errors which are fundamental in any three primary colour additive reproducing system, by electrically changing the R, G, and B signals with a matrix or masking amplifier which mixes (usually subtracts) the signals in a very precise predetermined amount. The form is generally as follows: R out = R in + a(G-R) + b(R-B) a, b, c, d, e, and f are G out = G in + c(G-R) + d(B-G) referred to as the masking B out = B in + e(R-B) + f(B-G) or correction coefficients
Industry:Entertainment
A video signal level below which no light should be emitted from a TV screen (the level at which the screen is blanked); also, that portion of the time that a video signal is transmitted when it is at or below blanking. These time portions can be divided into a horizontal blanking interval (HBI) and a vertical blanking interval (VBI). Since no picture information is carried in either blanking interval in an NTSC signal, various ATV schemes propose using them for carrying augmentation information, such as higher quality sound or widescreen panel information. Potentially conflicting with those schemes are other schemes that already use the blanking intervals for descrambling codes, test transmission, time code, and test and reference signals. Reducing the duration of the blanking intervals to allow more picture information to be transmitted potentially conflicts with the demands of the scanning circuitry of older TV sets. Sometimes this conflict is said to be resolved by bezel coverage and overscanning.
Industry:Entertainment
