DTL FontMaster Manual1.1 PDF

dtl ikarusmaster: outline description
Outline Description
The outlines of the glyphs in the font are described by the Ikarus format.
The ik format describes an outline by either straight lines or a Cubic spline
section, which is also a third-degree polynomial. Every point of the Ikarus
format lies exactly on the contour -in contrast to the Bezier format, where
control points are located outside the contour. Therefor the ik format is
ideal for working with a digitzing tablet for input.
For a long time the Ikarus format has been the de facto standard for
creating and manipulating digital fonts, and is still in use worldwide by
specialist type design houses. These demanding customers appreciate the
high quality of the digital data combined with the system’s flexibility, its
simplicity and the speed with which fonts can be digitized, edited and
converted into other data formats.
Four diuerent type of point are available to mark the contours:
1. Start points: only one start point for each contour is allowed. The
ideal location for a start point is at a corner. If there are no corner
points on the contour, the second best location is at the first (in
clockwise order) of two adjacent tangent points. If there are neither
corner nor tangent points, the start point should be placed at an
extreme curve point. Start points are marked in red by default.
2. Curve points: describe curved sections of the contour, by default
marked in dark blue.
3. Corner points: marking a non-continuous transition between two
straight sections, two curve sections or a curve and a straight line.
4. Tangent points: These points are marking a continuous tangential
transition from a straight line to a curve and vice versa. They are
marked in light blue by default.
120
Curve point
Start point (corner point)
Tangent point
note: The ik file format is
considered as a database
format. Currently one file
can contain up to 22000 glyphs.
Glyphs are identified by 2-byte
numbers (1–65535). The data
consists of header, contour header
and outline. There is no hinting
information in the data. For
PostScript Type 1, TrueType and
OpenType production additional
information is necessary and has
to be supplied via text files, like
ufm, afm, etc. (more info about
these text files can de found in the
appendices).
The format specification is
public and can be found in Dr.
Peter Karow’s Schrifttechnologie
(Berlin, 1992).
tip: If you use +
mouse click the program
will change the label from Anchor
to Smooth Anchor point and vise
versa. Using the Change Label
function from the Function Tool
Bar makes it possible to change
straight lines into curves and vice
versa, this way adding and
removing Control points.
Tangent points are forcing tangent
continuity between the adjacent
sections.