Does still some philosophy exist for the halftone frequency selection?

Being a fundamental parameter in TV system the number of strokes of TV screen doesn't depend on its size and is strictly determined by the broadcast standard. To the contrary; information content of a print is squared with the increase of a picture linear dimension as well as of its halftone frequency. Carrying the same data volume the image of 140 Lpi occupies twice less of a page area as compared to the 100 Lpi one. Ruling of a halftone for given job is taken within the most common range of 60 - 200 Lpi from a set of the numbers which were empirically found at times of photoengraving. Digital pre-press of to day can provide flexible adjustment of a ruling value. Performance of an ink - press - paper system is subject to a great variety of factors therefore the standardization of frequencies is problematic for halftone printing as compared to electronic media. Ideas of determining screen ruling for particular printing conditions are discussed with taking into account: - conflicting demands of providing both spatial and tonal resolution; - formal and effective tone range of a print; - noise level of a printing process; - unity of the extreme dot area meanings for different screens; - behaviour of vision as the low pass filter with an adaptive spatial frequency threshold.