[NTG-context] Detect an empty page of a .pdf?

Hello, is there a ConTeXt-Lua way to detect whether i-th page of a .pdf is empty (meaning "has no text on it")? Best regards, Lukas -- Ing. Lukáš Procházka | mailto:LPr@pontex.cz Pontex s. r. o. | mailto:pontex@pontex.cz | http://www.pontex.cz Bezová 1658 147 14 Praha 4 Tel: +420 241 096 751 Fax: +420 244 461 038