Illumination light quantity setting method in image measuring instrument

An illumination light quantity setting method in an image measuring instrument including an image pickup that images a plurality of measured points based on a preset measuring procedure, and an illuminator that irradiates the measured points with light having illumination light quantity corresponding to a provided command signal, the image measuring instrument measuring a dimension and a shape of a to-be-measured object while the illuminator irradiates the measured points with light having illumination light quantity corresponding to an illumination preset value with reference to the illumination preset value that is preliminarily set and stored for each of the measured points, the setting method comprising:

• a command signal output step that outputs the command signal for irradiating light having the illumination light quantity corresponding to the illumination preset value for each of the measured points;
• an offset value assigning step that assigns an offset value to the command signal to be sent to the illuminator, the offset value being a common value, and the command signal being applicable to all of the measured points;
• and
• a setting step that sets the offset value to be variable without modifying the illumination preset value for every measured point.