Some Experience of the Subjective Evaluation of Quality of Blocks and Prints.

By subjective evaluation a jury of photo-engravers ranked a number of halftone blocks, made from the same photographic original, in quite another order than printers, who printed the same blocks. The material was studied at the Graphic Arts Research Laboratory, where pair comparison was used in ranking several different sets of prints, but nor in this way any correlation was found with the photo-engravers' evaluation. From thorough microscopic studies of the blocks and the prints it seemed probably that certain faults in the dot formation, specially connections in the highlights and too small pinholes in the shadows had effected the rejection of the low-ranked prints.