Printing apparatus

A printing apparatus comprising:

• an exposing head having a plurality of light control elements arranged in a primary scanning direction, said exposing head and a photosensitive material being movable relative to each other in a secondary scanning direction perpendicular to said primary scanning direction, said light control elements being controllable, in time of the relative movement, based on set exposure data to create a test chart;
• a scanner for scanning said test chart to acquire scanning data;
• and
• a correction data generating means for setting correction data to said light control elements based on said scanning data;
• wherein
• a test print means is provided for forming, on said test chart, a plurality of pixel lines by exposure with said light control elements, and indices indicating an exposure start side and an exposure end side in said secondary scanning direction based on exposure with the same light control element;
• and
• said correction data generating means performs a sampling point setting process including a process for setting ends of said plurality of pixel lines from said scanning data, a process for setting a virtual line extending between the index on said exposure start side and the index on said exposure end side, and a process for setting sampling points on a scanning line parallel to said virtual line with reference to the ends of said pixel lines, and a correction data generating process for generating said correction data based on the density data of said sampling points set in said sampling point setting process.