In most Gothic typefaces, no contrast can be found, while other Gothics have a light contrast. Roman typefaces, on the other hand, often have distinctively contrasting stroke widths. Therefore, one would expect that contrast has received attention in research. However, it seems that only Ovink (1938) has studied contrast. He tested each separate letter of the alphabet, printed in several typefaces, for ease of recognition. His conclusions, however, went beyond contrast alone. Consequently, nothing can be said about the unique effect of contrast. Some designers argue that it results in greater legibility, pointing to the deliberate increase of contrast in Roman designs throughout design history, but no scientific support is found for this assumption.

Note that the kind of contrast discussed above should not be confused with background contrast or environmental contrast. Background contrast is the difference in lightness between characters and their (paper) background. Environmental contrast is used to make information stand out from its total surroundings (conspicuous); this property is important for road signs, for instance. In most literature, it is not indicated which kind of contrast is meant. However, contrast in stroke width is usually an issue in typographers’ publications, whereas ergonomists are mostly concerned about contrast with background or environment.

When discussing the optimal stroke width -to- height ratio, the effect of background contrast and illumination should be considered. Background contrast is created by variation of color (-brightness) (Tinker, 1931; Zachrisson, 1965) and background material (Foster, 1980). When we look at the most common combination black print on a white background and assume good background contrast, the following optimal ratios have been found. Under conditions of reasonably good lighting, a stroke width -to- height ratio of 1:6 to 1:8 (0.167 to 0.125) is suggested. Soar (1954) suggests that even a ratio of 1:10 (0.1) is possible for numerals. With reduced illumination, a lower ratio (higher proportion) is required to maintain the same level of legibility; bold type with a ratio of 1:5 (0.2) is suggested for low levels of illumination (Heglin, 1973). The same applies to situations in which the background is highly luminous. When the letters are transilluminated, the ratio can be set at 1:12 to 1:20 (0.083 to 0.05) (Sanders and McCormick, 1993). For applications such as posters, Ovink (1938) proposes a ratio of 1:5 (0.2) under normal circumstances, arguing that this would result in a better balance between conspicuity and legibility.

Spencer, Reynolds and Coe (1975) have compared four typefaces to determine which are the least sensitive to degradation of image quality because of low-quality printing or deforming background material. Of Baskerville, Rockwell, Times and Univers, the latter two were suggested for use in "situations where thinning-down and thickening-up of the image are likely to occur". This means, that setting text in Times or Univers would more likely resulted in maintained legibility than setting it in one of the alternatives.