Abstract: Apparatus for measuring pattern area percentage of engraving film with a transparent member for placing the film thereon, an optical device having a light source and light receiving unit, a moving device for relatively moving the transparent member and the optical device, and a control device which has a memory for storing the data concerning the light transmission quantities given by the optical device and a calculating device for calculating pattern area percentage corresponding to each column defined on the printing plate of a printing machine used. The number and width of columns of the printing plate varies depending on the number and spacings of ink supply keys. The control device controls the moving device which moves the placing member in the direction of each column. The optical device has a slit which width can be changed in accordance with the number and widths of ink supply keys mounted on a primary machine used.

Abstract: In an apparatus which measures an area factor of an image portion of an image-bearing member, such as a printing plate used in an offset press, having image and non-image portions with different reflectivities, a single light source and a single photoelectric conversion element are used for measuring reflected light from the image-bearing member by optically scanning the image-bearing member. An arithmetic operation unit is provided so that the reflected light data are measured on the basis of electrical signals from the photoelectric conversion element each time a light beam moves for a unit distance in the X axis direction of the image-bearing member, and the corresponding reflected light data are added in the Y axis direction to obtain area data for each unit region in the X axis direction.