Patent ID: 7140298

Claim:
A method for evaluating planographic printing plates, comprising the steps of: (a) preparing a planographic printing plate precursor having a support and a photosensitive layer provided on the support, the photosensitive layer containing an aqueous alkaline solution-soluble resin and a compound that generates heat by absorbing light; (b) setting one image using as a reference a length of a side of one pixel of predetermined resolution; (c) setting at least one other image using as a reference a length of two to eight pixels of the predetermined resolution; (d) irradiating the one image and the at least one other image on the photosensitive layer by incrementally altering plate-surface energy; (e) forming a standard developer-processed planographic printing plate by developing an exposed planographic printing plate with a standard developer; (f) identifying an exposure intensity that respectively provides the one image and the at least one other image formed on the standard developer-processed planographic printing plate with identical density; (g) forming a test developer-processed planographic printing plate by developing a planographic printing plate prepared and exposed under the same conditions as in the steps (a) to (d), with a developer to be evaluated; (h) identifying an exposure intensity that respectively provides the one image and the at least one other image formed on the test developer-processed planographic printing plate with identical density; and (i) comparing the exposure intensity determined in the step (f), which respectively provides the one image and the at least one other image formed on the standard developer-processed planographic printing plate with identical density, with the exposure intensity obtained in the step (h), which respectively provides the one image and the at least one other image formed on the test developer-processed planographic printing plate developer with identical density.