To obtain a profile of necessary quantity of ink by reading an outputted printing plate image in a printing direction by an image reading device and accumulating density value of obtained image data in the printing direction at regular intervals.

In a composing device 1 and a plate-making device or process, a picture pattern 4 which is the same as a picture pattern of a printing plate is previously outputted to a printing plate image output means 3 such as a plain paper printer. Here, an outputted matter of the outputted printing plate image is read by an image reading device 5 and is stored temporarily in an image memory means 6 as an image data. The stored image data is accumulated in a cross direction of printing by an image accumulating device 7 at every fixed interval, for example, at an interval on the printing plate image equivalent to an interval with which an ink adjusting keys of a printer are arranged, so that a density accumulation profile 8 in the cross direction of a printing matter image is obtained. In the image reading device which accumulates reflection density data of the printing plate image from a large number of light receiving elements at a density receiving section, the cost can be reduced further largely.