Legibility of condensed perceptually-tuned grayscale fonts

The authors analyze the quality of condensed text on LCD displays, generated with unhinted and hinted bilevel characters, with traditional anti-aliased and with perceptually-tuned grayscale characters. Hinted bi-level characters and perceptually-tuned grayscale characters improve the quality of displayed small size characters (8pt, 6pt) up to a line condensation factor of 80%. At higher condensation factors, the text becomes partly illegible. In such situations, traditional anti-aliased grayscale character seems to be the most robust variant. They explore the utility of perceptually-tuned grayscale fonts for improving the legibility of condensed text. A small advantage was found for text searching, compared to bilevel fonts. This advantage is consistent with human vision models applied to readin

Perceptually-tuned grayscale characters based on parametrisable component fonts

Our component-based parametrisable font system is a newly developed font description and reproduction technology. It incorporates for each basic character shape a software method responsible for the synthesis of an instance of that character. A given font is synthesized by providing appropriate font parameters to these character synthesis methods. Numerous concrete fonts can be derived by simply varying the parameters. Such variations offer high flexibility for synthesizing derived fonts (variations in condensation, weight and contrast) and enable saving a considerable amount of storage space. We show that with component-based parametrisable fonts, high quality perceptually-tuned grayscale characters can be generated without requiring hinting information. Generating perceptually-tuned grayscale characters with parametrized component-based fonts consists in automatically adapting the phase of some of the character's parameters in respect to the underlying grid and in ensuring that thin character parts are strong enough not to disappear (weight-control). The presented method is especially powerful for generating high-quality characters on LCD displays (cellular phones, pen-computers, electronic books, etc..

Legibility of Condensed Perceptually-Tuned Grayscale Fonts

Abstract. We analyze the quality of condensed text on LCD displays, generated with unhinted and hinted bilevel characters, with traditional anti-aliased and with perceptually-tuned grayscale characters. Hinted bi-level characters and perceptually-tuned grayscale characters improve the quality of displayed small size characters (8pt, 6pt) up to a line condensation factor of 80%. At higher condensation factors, the text becomes partly illegible. In such situations, traditional anti-aliased grayscale character seems to be the most robust variant. We explore the utility of perceptually-tuned grayscale fonts for improving the legibility of condensed text. A small advantage was found for text searching, compared to bilevel fonts. This advantage is consistent with human vision models applied to reading.

Human interaction with digital ink : legibility measurement and structural analysis

Literature suggests that it is possible to design and implement pen-based computer interfaces that resemble the use of pen and paper. These interfaces appear to allow users freedom in expressing ideas and seem to be familiar and easy to use. Different ideas have been put forward concerning this type of interface, however despite the commonality of aims and problems faced, there does not appear to be a common approach to their design and implementation. This thesis aims to progress the development of pen-based computer interfaces that resemble the use of pen and paper. To do this, a conceptual model is proposed for interfaces that enable interaction with "digital ink". This conceptual model is used to organize and analyse the broad range of literature related to pen-based interfaces, and to identify topics that are not sufficiently addressed by published research. Two issues highlighted by the model: digital ink legibility and digital ink structuring, are then investigated. In the first investigation, methods are devised to objectively and subjectively measure the legibility of handwritten script. These methods are then piloted in experiments that vary the horizontal rendering resolution of handwritten script displayed on a computer screen. Script legibility is shown to decrease with rendering resolution, after it drops below a threshold value. In the second investigation, the clustering of digital ink strokes into words is addressed. A method of rating the accuracy of clustering algorithms is proposed: the percentage of words spoiled. The clustering error rate is found to vary among different writers, for a clustering algorithm using the geometric features of both ink strokes, and the gaps between them. The work contributes a conceptual interface model, methods of measuring digital ink legibility, and techniques for investigating stroke clustering features, to the field of digital ink interaction research