The actual drawing the hundreds of glyphs required for a performant contemporary font may seem like an enormous amount of work, yet it is only half the effort involved in the development of a typeface. It is the quality of the spacing (and to a lesser extent kerning), the careful arrangement of space around the characters, that distinguishes a good typeface from a poor one. Without proper spacing, a typeface is nothing more than a barely usable collection of black shapes alternatively drifting apart or colliding into each other.
Reading involves deciphering the interaction between the black of the letter forms and the white surrounding the black. There are two types of space – the white inside the letters (except of course in letters like the capital ‘I’, the lowercase ‘l’ or the number ‘1’), and the white outside them. When drawing character shapes a typeface designer has to continuously balance those two types of space in order to create an even grey value of the text; the amount of white inside a glyph influences how much white needs to be outside the glyph. This ‘grey value’ determines how pleasant and effortless the reading experience will be. This is why it is vital to space the glyphs as you are drawing them when designing a typeface. Drawing and spacing are intrinsically connected and need to happen simultaneously.
The design of a typeface relies on the tension between difference and similarity. The character shapes need to be similar to achieve a harmonious appearance, yet different enough from each other to be easily identifiable. When we examine the characters in a typeface, we see these different shapes create different types of space – for example the white can be entirely inside the shape, like the counter in the ‘o’, or can be partly inside and partly outside the shape, like the white between the bowl and the loop in a double-storey ‘g’. All the glyphs also have white outside the shape: left and right, above and underneath. For the purpose of this article we will restrict ourselves to the white left and right.
The basic challenge the typeface designer faces is that she has control over only half of the space to the left and half of the space to the right at a time. Because the characters, not the spaces are the basic units in a typeface, the spaces between the characters need to be cut in two so that individual characters can be arranged to set text. The designer needs to decide where the left half of the space ends and stick it to the right side of the character on the left. The other half of the space belongs to the left side of the character on the right. You can easily visualise this when you look at metal type. Today’s bounding box around each character is a digital representation of the physical piece of lead the character used to sit upon. The distance from the left or rightmost extremity of a glyph to the edge of the space is called the side bearing.
Thus the space between any given character and the preceding one is actually created by sticking together two half spaces – the space at the left side of this character with the space to the right side of the preceding character. The opposite applies to the space between the character and the one following it. This is why the spaces left and right of any given character are ever-changing, as they depend on what other glyphs precede and follow that character. The only way to tackle this problem is to constantly check the spacing in test strings of different sequences of characters during the drawing process. Most typeface designers start with a round shape like the ‘o’ and a straight-sided shape like the ‘n’ and expand from there. You cannot first draw all the glyphs and then come back to define the side bearings afterwards. This is the reason why drawing an alphabet in Adobe Illustrator before importing it in a font editor might not be a good idea.
Character spaces can be divided into a number of basic categories according to their shapes: rectangular ones next to characters with vertical sides, curved ones next to round characters, triangular ones, and then a few exceptions for unique characters like ‘a’, ‘g’, ‘s’, ‘x’, etc. This helps type designers introduce consistent spacing in characters with similar shapes – for example the left bearing of an ‘e’ will be similar to the ‘c’, ‘d’, ‘o’, and ‘q’, and the right bearing of an ‘h’ will be similar to the ‘m’ and ‘n’. Unfortunately this system will get you but so far, and it takes the eye of a skilled type designer to space all the glyphs in a typeface well. The quality of the spacing often gives away the level of proficiency of the type designer.
Yet even the best type designer cannot find a perfect spacing solution for every single character combination. As a last resort she will have to kern specific glyph pairs to correct the unavoidable shortcomings in the spacing. This is the topic of the next article in this series.
Due to their very nature different rules apply to monospaced (also called fixed-width) fonts. In proportional typefaces the bounding boxes are of varying widths: they are defined by the width of the glyph plus the side-bearings. As their name implies the bounding boxes in monospace fonts all have the same fixed width, and no kerning is needed. The character shapes need to adapt within this fixed space to distribute the inner and outer white space as best as possible. This produces a much more uneven grey value.
Because I don’t really feel qualified to discuss spacing in non-Latin scripts, Latin-based alphabet systems (so Cyrillic and Greek as well) are the focus of this article series. Generally speaking most scripts tackle spacing in similar ways, adapted to their specific structure and rules.
For more on this subject I highly recommend Inside Paragraphs, the book by awarded typeface designer Cyrus Highsmith that I reviewed for The FontFeed. It is a great primer exploring the interrelationships between character, word, line and paragraph, all by focusing on the space between them.
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