Method for evaluating planographic printing plates and quality-control method thereof

Abstract

A method for evaluating planographic printing plates according to the present invention includes: a step (A) of exposing a planographic printing plate precursor by irradiating a thin-line image of a one-pixel line and at least one thin-line image selected from two- to eight-pixel lines by incrementally altering the plate-surface energy; developing the exposed plate precursor with a standard developer; and identifying an exposure intensity (hereinafter, 'thin-line sensitivity') that respectively provides the images thus formed, with the same density; a step (B) of preparing another planographic printing plate precursor under the same conditions as in the step (A) and identifying the thin-line sensitivity, except that the planographic printing plate precursor is developed with a test developer; a step (C) of comparing the thin-line sensitivities respectively obtained in the steps (A) and (B); and a step (D) of adjusting plate-making conditions when the results of the comparison in the step (C) show a difference between the respective thin-line sensitivities that exceeds a predetermined value.