An image quality survey has demonstrated that text quality in terms of its apparent weight (i.e., character broadening) is well represented by measurement of the width of lowercase L's. The survey has shown that an l-width of about 410 μm for fonts of 12-pt Times Roman style is the preferred width for prints produced by today's copiers and printers. The survey was run using two methods: (1) paired comparisons and (2) acceptability judgment. Both methods gave virtually identical results indicating that the method of paired comparisons using a limited number of internal judges may be a good surrogate for otherwise extensive image quality surveys made in the field.
J. Raymond Edinger, Catherine Newell, "Subjective Impression of the Weight of Text Correlates with Measured L-Width" in Journal of Imaging Science and Technology, 1997, pp 174 - 177, https://doi.org/10.2352/J.ImagingSci.Technol.1997.41.2.art00012