The interlace method was developed for TV broadcasting because the allotted bandwidth for TV channels, defined more than a half century ago, was not sufficient to transmit 60 full frames per second. Interlacing with 60 half frames was visually better for moving images than 30 non-interlaced full frames.
Interlace Vs. Progressive Scan
Interlaced screens display every other line (1-3-5 etc., then 2-4-6, etc.), while non-interlaced screens, known as "progressive scan," display lines consecutively (1-2-3 etc.).
All non-digital TVs are interlaced. Older CRT computer monitors were also interlaced at their highest resolution and progressive scan at lower resolutions. Some digital TV standards are interlaced, such as the high-definition 1080i format, and HDTV sets support both interlaced and progressive scan signals (see HDTV).
Modern CRT and flat panel computer monitors are all progressive scan. See deinterlace, vertical scan frequency and interlaced GIF.
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interlace [¦in·tər¦lās]
| interlace - progressive coding |
Interlace
the arrangement of yarns in woven, knitted, and curtain fabrics that determines their structure, appearance, and properties.
In woven fabrics, the interlace is always characterized by perpendicular systems of yarns: the warp and the filling. (In openwork interlace, there is a supplementary system of warp yarns, known as cross-woven threads.) The choice of an interlace depends on the intended use of the fabric and the type of yarn from which it is made.
There are conventional methods of graphically showing the interlace of a fabric on paper. A diagram of the interlace is made by a system of boxes: the black boxes (risers) show the crossings, or floats, of the warp yarns, and the white boxes (sinkers) show the floats of the filling yarns. Each vertical row of boxes depicts a wale, and each horizontal row, a course.
Every interlace is based on a definite number of warp yarns and filling yarns. The smallest number of yarns used before the order of their interlacing is repeated is called the repeat. The order of interlaces of warp and filling for each row may be expressed as a fraction, in which the numerator shows the number of consecutive yarns that the warp floats over and the denominator represents the number of consecutive threads that the filling thread floats over. The rows may differ from one another. They may be nonparallel to each other, forming a definite angle of displacement. The angle is included in the description of the interlace. Complex interlacing is characterized by warp and filling fibers in not just one but several layers. The number of possible interlaces is very great.
Depending on their complexity, interlaces are divided into basic (plain, twill, and satin), small-figured (dobby weaves), complex, and large-figured (Jacquard) weaves. Most widespread are basic interlaces.
The number of possible interlaces is limitless theoretically but, from a practical standpoint, is limited by technological feasibility, aesthetic considerations, and usefulness. Interlaces are reproduced by using the warp-shedding mechanisms of the loom: the simpler looms use sinker cams, and the more complex use dobby attachments or Jacquard machines.
Knit interlaces are characterized by the form of the yarn loops and their arrangement. The fabrics are divided into flat and warp knits. In flat-knitted fabric, the horizontal rows of loops are formed by a single strand, and in warp knitted fabric, by a great number of warp strands. Knit interlaces are distinguished according to structure as plain (jersey), ribbed, combined, and complex.
REFERENCES
Stroenie i proektirovanie tkanei. Moscow, 1953.Iudenich, G. V. Perepletenie i analiz tkanei. Moscow, 1968.
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