After struggling in its early years, the business of networked digital displays in retail and other public spaces - a "narrowcasting" segment - is now on the path to sustainable growth, according to an InfoTrends study, "Narrowcasting: The Opportunity for Digital Signage and In-Store TV Networks," writes MarketingCharts.

At the end of 2006, the narrowcasting industry was valued at $1.1 billion with an installed base of 630,000 screens at 97,000 sites - a compound annual growth rate (CAGR) of 56 percent from 2004 to 2006, and the first time that the narrowcasting industry has exceeded estimates, according to InfoTrends.

InfoTrends forecasts CAGRs of 18.5 percent for revenues, 8.9 percent for sites, and 11.9 percent for screens between 2006 and 2011. By 2011, total revenues are expected to reach $2.59 billion.

The typical survey respondent - managers involved in buying, designing, placing out-of-home media - is using five different types of media, with printed signage and outdoor signs still the most common, according to InfoTrends.

MarketingCharts provides some additional findings from the survey.