Pagination may be described as the process of producing good page layouts for given material. It is a clearly distinguishable task in the prepress phase of a newspaper [Ahonen and Viertiö, 1989], and its abstraction can be extended to the generalized newspaper as well. Newspaper pagination includes two main subtasks: (1) distributing given material onto a range of pages and (2) preparing the presentation of the material, i.e. the page layout.
Successful pagination requires a preprocess that maps the logical structure of a newspaper to the physical structure, which is defined by the printing press configuration or the restrictions of other visualization media. In newspaper pagination in particular, this translates to taking into account such things as what pages contain colour, which is the middle sheet of the newspaper and what constraints are imposed by the printing machines and process. The latter include such visual constraints as what is the smallest visible font size or the resolution of figures, and constraints adressing the content such as placing cut-out coupons on the edges of pages instead of on opposite sides of the same physical page, or distributing advertisements from competitors on different pages.
In pagination of the generalized newspaper there is often an abundance of material with different priorities and expiration times, instead of a strictly selected set of material that must be fitted into the publication. The material for a traditional newspaper may be extracted from a large article database. Many database queries as well as WWW searches now produce hits with methods such as scoring, giving only a priority value for the hits. In other cases the aim may be to display a fixed set of material while minimizing the total space. Therefore, the pagination task may be either one of the following:
The first case arises in practice e.g. in pagination of telephone directories and newspaper advertisement sections. The second case is more common with pagination of editorial material. In both cases, devising page layouts is required. In other words, the general goal of pagination is to form good page layouts out of some material, where high quality is described in terms of constraints and/or optimization criteria. In this work both the above mentioned variations of the pagination problem are considered with emphasis on the general problem of producing good page layouts.
Since the goal of pagination is to produce good page layouts, it is necessary to specify what the goodness of a page entails. Page layout provides a way to catch and direct the user's attention, control the order in which different parts are read and for how long time. It is also a way to visually group, divide and structure information and present it in an easily readable and aesthetically appealing way [Veijonen et al., 1994]. In addition, all this must be carried out efficiently, i.e. with as little waste of resources as possible. Three aspects of producing good page layouts may thus be identified: saving space on the medium, cognitive considerations and aesthetic considerations.
Table: Different goals and means of the interest groups of a generalized newspaper.
Aesthetic considerations play a major role when page layouts are designed by humans. This is also the most difficult aspect of the process to automate, because aesthetic appeal is not easily definable in terms of explicit rules. Nevertheless, to be able to take into account any aesthetic values in automatic pagination, it is necessary to have an idea of what makes a page aesthetically appealing.
Five main principles are identified in [Rehe, 1985]: organization, simplicity, contrast, balance and harmony or unity. Some similar discussion is carried out also in [Henning et al., 1988]. The questions for automating the pagination are, how to evaluate the fulfillment of these principles on existing pages and how to build pages that conform to these princples. Below are some practical suggestions for the design of page layouts: