Reversed type refers to text that has a light color on a darker background. When white text is set on a black background, the text is ‘knocked out’ and the paper shines through, hence the term ‘knockout text’. Reversed type doesn’t have to be white. The term is also used for text with a light color on a darker colored background.
Reversed type is often used to emphasize text. Because the use of dark background colors draws the attention of the reader, it should only be used sparingly on a page.
Usability research has shown that people sometimes ignore reversed type because they fail to notice the text. To avoid that people overlook the text in a reversed heading, it is a good idea to repeat its content in the text that follows.
Technical considerations when using reversed type
When reversed type gets printed, the ink has a tendency to spread into the type.
- The text should be large enough. Most offset printers recommend that reversed type is at least 10 point (or even 12 point for newspapers). Some printing processes (e.g. short run digital prints) may support smaller font sizes such as 8 point.
- If you use a serif font, some of the sharp edges of the serifs may disappear. Some serif fonts have thin horizontal strokes which may clog up. In general sans serif fonts are more suitable for reversed type.
- If the typeface you want to use is available in different weights, choosing a bold or black variant is a good idea. With thicker stems and strokes, the spreading of ink has less effect on the legibility of the text. As a general rule, make sure that the thinnest lines have a minimum thickness of 0.5 point or 0.15 millimeter.
- Don’t use script fonts for reversed type. Usually these typefaces are so delicate that the printed result will be unreadable.
When the background gets printed in more than one color, trapping can become an issue. Trapping is a technique that is used to minimize the effects of printing colors that are not printed in perfect registration. Imagine you use rich black for reversed type but no trapping is applied and the cyan color is printed slightly out of register. The end result could look like this.
Usually the prepress team of a printer or service bureau will trap the job to avoid the above issue. Sometimes, however, they cannot do this so easily, for instance when you create reversed type in Photoshop by putting outlined white text on top of a photograph. It is better not to reverse text inside bitmap images. Designers need to be aware that reversed type can be more difficult to print. In case of doubt contact the printer for advice.
If the reversed text is fairly small, has a color and the job will be printed using a coarse screen ruling (like with newsprint), it is better to use flat tints or a color mix in which the dominant colors are at least 70 percent. This makes sure that the dots of the screening don’t break up the character shapes of the text, as I’ve tried to illustrate below.
- Increase the leading between lines of reversed type to improve the legibility of the text. Sometimes it also helps to increase the letter space a bit.
- Add a drop shadow to type that is reversed on a busy photograph. It will make the text stand out a bit more on the cluttered background.
- Make sure there is enough contrast between the text and the background.
Other sources of information
The Simpleton has a nice article about using reversed type for headings or lists.