Abstract: A process for the production of an aqueous suspension of hydroxylapatite from calcium hydroxide or calcium oxide, and phosphoric acid in which, while stirring, phosphoric acid is slowly added to an aqueous solution or suspension of the calcium compound up to a calcium/phosphorus mole ratio of 10:6, wherein the course of the reaction and the achievement of the end point of the reaction is determined by the conductivity of the solution or suspension. The process results in the production of essentially pure hydroxylapatite, which is useful as, for example, a teeth cleaning agent, a bone-replacement, or as a carrier material for pharmaceutical compositions.

Abstract: A method for automatic recognition of white blocks as well as text, graphics and/or gray image areas on a printed master employs the steps of optoelectronically scanning the master and converting the analog scanning signals into digital signals such that a binarily encoded representation of the master is generated. Horizontal and vertical white blocks are successively searched for in the binary image and the locations of such white blocks are stored. The binary image thus subdivided by horizontal white blocks and the binary image subdivided by vertical white blocks are logically linked to one another in order to locate white "frames" for the individual areas of the printed matter. Such printed master areas formed in white are subsequently statistically analyzed in order to determine whether the framed area represents a text, graphics or gray image area on the printed master.

Abstract: An apparatus and method for automatic recognition of image and text/graphics areas on a master undertake an opto-electronic scanning of the master with analog values obtained by the scanning being sampled and converted into digital information which is stored in a data field which is divided into a number of windows having edge lengths selected to be greater than the spacing between two successive lines of text. A grayscale value histogram is generated for each window and is statistically analyzed for determining whether the area of the master represented by the window is predominantly a text/graphics area or an image area based on known statistical characteristics generally related to each type of area.