Interpreting the two types of fonts commonly used in prepress

Pre-press common fonts are divided into front-end display fonts, namely TrueType (referred to as TT) fonts (suffixed with .ttf) and back-end output fonts, namely PostScript fonts (suffixed with .CID). The former is often used for low-resolution display, suitable for book, newspaper, Office, CorelDRAW, Illustrator and other software, the latter is suitable for output on high-resolution devices, suitable for RIP, Eleccroc.

1.IT font

The TrueType font format is a new digital glyph description technology jointly proposed by Apple Inc. and Microsoft Corporation of the United States. TT is a set of richly colored instructions for color contour functions that describe the outline of a font. These instructions include font construction, color padding, numeric description functions, process condition control, and raster processor (TT processor) control. Additional prompt information control and other instructions.

TT uses the quadratic B-spline curve and line in geometry to describe the outline of the font. The quadratic B-spline curve has first-order continuity and tangent continuity. The parabola can be accurately represented by a quadratic B-spline curve. The more complex font shape can be represented by the mathematical characteristics of the B-like long curve by a series of connected quadratic B-spline curves and straight lines.

The TT font can be used both as a print font and as a screen display. Since it is described by an instruction for a glyph, it is independent of resolution. The output is always output according to the resolution of the printer, regardless of the enlargement or reduction. It is smooth and will not appear jagged.

2.CID font library

The CID font library is the latest font published by Adobe Corporation of the United States. It has the characteristics of easy expansion, fast speed, good compatibility, simplicity and flexibility. It has become a hot spot in the development of Chinese fonts.

CID (character idenlifier) ​​is a character identification code. The total character set includes all the commonly used characters in a specific language. The characters are sorted. The order number of the characters in the total character set is the CID identification code of each character; CMap(character) Map) character mapping file, which maps the encoding of the character to the CID identification code of the character, and then uses the CID identification code to obtain the glyph information from the CIDFont file.

All glyph descriptions of the CID font are in PostScript Type 1 format, which guarantees high quality output across platforms.