What Are Kerning Pairs?
The terminology relating to kerning and kerning pairs is connected to desktop publishing. Depending on typeface, the characters and spacing are relevant aesthetically.
Kerning is the term given to the adjustment of space between letters of a font. Desktop publishing designers refer to the spacing as making the difference between an average or great design. Visually a well-spaced arrangement of letters will be easier to read and thus easier to comprehend.
Spacing is a key aspect of typography. The amount of space that exists between the characters or glyphs creates an impression of the text being open or constricted. Kerning refers particularly to the adjustment of space between two specific characters. Thus the term kerning pairs is used.
Kerning pairs or kern pairs are designed together so that they fit well. The adjustment is made when the normal space that exists between them is not considered optimum for comfortable viewing.
Certain kern pairs are placed together naturally. A and V are a common kern pair. When these two letters are typed next to each other, the way the diagonals of the letters are formed, the spacing appears inappropriately open. Kerning changes the spacing between the A and V kern pair so that it is visually appealing and comfortable to look at. Further typical examples of kern pairs are “To” and “Va” as both need adjustment to space configuration. “Ya” is another kern pair example.
Many design programs have a built in font spacing capacity. When this is done automatically, the spacing has already been set up in such a way that it is conducive to optimum viewing. Adjustment is not necessary and kerning occurs spontaneously. Thus by typing in the letters the built in kerning mechanism places the characters into well-fitting combinations. These kern pairs may range between 50 in a particular font, 200 to 300 in another, and up to several thousand that may appear as kern pairs in a well-designed advanced program.
When there is not an automatic adjustment or kerning and kern pairs are not set as the default, certain software programs allow one to operate the mechanism of kerning manually. Manual kerning involves adjusting the space between two characters once all other feature adjustment options have been made. There are also times where someone may have a favorite font but the spacing or kerning is not appropriate; in this instance certain design programs have a method of creating typographical changes. When using a combination of fonts and styles as well as different sizes, manual kerning may also be used.
Kerning and kerning pairs are associated with names and applications such as kerning tables, kerning values, and the kerning field in which they appear.
A kerning table contains what is specified as the kerning values. These values are given as the numerical value points determining the amount of space that is required or the adjustment needed to be created between the letters. Thus one talks about kerning values of the kern pair. For example in a design program the kerning value may be displayed in the kerning field when clicking on the insertion point between the two characters.
When a limit is set on the amount of adjustment to spacing that can take place, this is referred to as minimum value. A combination of kerning and tracking may also be required. Tracking is a mechanism that adjusts space between a certain range of letters without regard to shape. Thus kerning is still needed.
The kerning mechanism, involving combinations of kerning or kern pairs, is set up as the optimum method of creating an optical image that is pleasing to the eye and enhances presentation and readability.
How to Set Up Kerning Pairs in FontLab?
In digital typography, a number is given to default character spacing in particular fonts. For example, -80 is the number directed to the kerning of ‘VA’ in Adobe’s Helvetica font. Common kerned pairs including ‘Wa’, ‘Ya’ and ‘to.’ Not all programs can access or read kerning pairs. There are programs that are able to create and edit the kerning pairs such as FontLab 4.6. FontLab 4.6 is a powerful font editor that allows designers to manipulate, edit and create fonts as well as kerning pairs.
Pairs can be set up in FontLab 4.6 and later versions of the software through the Metrics Window. This Window was created by the Dutch type designer, Lecas de Groot, who became a master of creating kerning tools. The first step is to select the Classes panel. In this panel, the designer can group the different glyphs into classes. The aim of the Kerning Classes is to allow the user to associate glymphs that have the same kerning values.
FontLab’s class builder assists in this process as it analyzes the shapes and curves of the glyphs. Letters that have the same curves on a particular side are automatically classed together. These characters therefore can use the same kerning value if they appear as the second value in the kerning pair. Users are able to name the pairs how they like. New glyphs with the same shape will automatically feature in the group. The spacing within the pairs can be monitored through the Metric Window. The designer is able to view the whitespace distribution between both the characters and lines of text. There are four modes within this window; preview, text, kerning and metrics.
The preview mode allows the designer to view all of the necessary and hidden marks and lines. This allows the designer to view the typeface and a print sample simultaneously and therefore apply any changes if necessary. Text mode is basically a text editor where the designer can apply all the simple text editing functions such as select, text, copy and paste. The designer is able to define kerning pairs for fonts within the Kerning mode. This is achieved either visually or numerically. Visually it is created through the use of the mouse or keyboard and numerically it is completed through entering numerical values into the appropriate fields. The metrics mode allows the user to edit these glyph metrics.
There are specific keys that aid this process. If one holds down the control button together with the Page up/Page down button, he or she is are able to quickly switch between the various predefined sample texts. The right and left curser keys allow the designer to move the glyph within the current advance width. If the designer holds down the shift key, the movement is constrained by 10 units. If designers hold down the control and command buttons simultaneously, they are able to modify the left sidebearing. If they hold down the control, command and alt button, they are able to manipulate the right sidebearing. FontLab also is able to generate metrics and kernings automatically. However, many designers do not opt in for this automatic process as the algorithm used is not particularly good.
Resources about Kerning Pairs
Microsoft Office Document about Understanding Typography
Adobe InDesign CS3 Advanced Character Formatting
PDF Understanding Typography
Typophile conversation about Kerning Pairs
Adobe information about Kerning that includes information about;Why is kerning necessary?, How kerning data is created?, Where kerning data is stored?, and many other topics
Bill Ross's Tweets