Patent ID: 7483045

Claim:
A printing apparatus comprising: an exposure head on which a plurality of light amount control sections are arranged in a main scanning direction, wherein a test chart is created by the relative movement between the exposure head and a photosensitive material in a sub scanning direction that is perpendicular to the main scanning direction and by controlling the light amount control sections of the exposure head based on set exposure data during the relative movement, a scanner for acquiring scanning data by scanning the test chart, correction data generating means by which correction data for the light amount control sections is generated based on the scanning data and stored in a correction table, and test printing means for creating the test chart on the photosensitive material by performing exposure based on the exposure data, wherein a code portion indicating a type of the photosensitive material is formed on the test chart, and a table setting routine that is provided in the correction data generating means performs a photosensitive material specifying process for specifying the type of the photosensitive material by extracting the code portion from the scanning data, a density data acquiring process for specifying a plurality of pixel lines corresponding to the plurality of light amount control sections from among the scanning data and acquiring density data for each of the pixel lines, and a correction data storing process for generating the correction data based on the density data that has been acquired in the density data acquiring process and storing the generated correction data in the correction table in association with the type of the photosensitive material that has been specified in the photosensitive material specifying process; and wherein the test printing means creates a plurality of said test charts each having the code portion, by setting a plurality of sheets of the photosensitive material having a width shorter than an exposable area in the main scanning direction of the exposure head, at different positions in the main scanning direction of the exposure head, and performing exposure based on the exposure data, and the correction data generating means creates a single test chart by acquiring densities of pixel lines that are formed in exposure performed by the same light amount control section, on overlapping portions in the main scanning direction of the exposure head, from among the scanning data of the plurality of test charts, then adjusting the density of one of said pixel lines on at least one test chart so as to make the densities of the pixel lines be in agreement, and, after the density has been adjusted, performing a combination in such a manner that the plurality of test charts are joined together at the overlapping portions.