Dot pitch (sometimes called line pitch, phosphor pitch or pixel pitch) is a specification for a computer display, computer printer, image scanner or other pixel-based device that describes the distance, for example, between dots (sub-pixels) of the same color on the inside of a display screen. In the case of a color display dot pitch is a measure of the size of a triad plus the distance between the triads.
Dot pitch may be measured in linear units, usually millimetres, with a smaller number meaning closer spacing, or in dots per linear unit, for example dots per inch, with a larger number meaning closer spacing. Closer spacing generally produces a sharper image (as there are more pixels in a given area). However, other factors may affect image quality, including:
- measurement method not documented, complicated by general ignorance of the existence of multiple methods
- pixel spacing varying across screen area (e.g., increasing in corners compared to center)
- differing pixel geometries
- differing screen resolutions when attempting to judge picture quality
- tightness of electron beam focus and aim (in CRTs)
- differing aspect ratios
Traditionally, dot pitch in displays has been measured on the diagonal, as this gives the most accurate representation of image quality. Starting about the mid-1990s, however, some companies introduced a horizontal dot pitch as a marketing ploy[citation needed]. By measuring only the horizontal component of the dot pitch and ignoring the vertical component, even a cheap, low-quality monitor could be awarded a small-seeming dot pitch.
The exact difference between horizontal and diagonal dot pitch varies with the design of the monitor (see pixel geometry and widescreen), but a typical entry-level 0.28 mm (diagonal) monitor has a horizontal pitch of 0.24 or 0.25 mm, a good quality 0.26 mm (diagonal) unit has a horizontal pitch of 0.22 mm.
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Originally Posted by JLS
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