Electrophotographic technology of a digital printing of a type “Computer-to-Print” is based on a reversible developing of an discharged electrophotographic covering with laser beam. An imaging of separated Lines (Line Development) of a Text Information is formed on a surface of the electrophot6ographic covering. This imaging is a fine point structure. The superposition of these Lines in the form of a raster creates a fine spatial lattice of filled fields (Largearea Development) of halftone imaging information (Largearea Development). Digital printing is a totality of these elements on the outputing document that visual perceived as imaging. The estimation method of developing conditions of an imaging basic element (rarefied trace of a separated Line) at digital printing is offered. For this purpose socalled “Zero Line” (ZL) of the electrostatic field in a zone of developing is used.