1. A non-transitory computer readable medium recording a calibration program, which causes a control device to execute calibration processing of reading as image data a patch sheet output from an image formation device, having a plurality of patch patterns formed as images based on different density-gradation value data and a marker patch formed from colors or gradation values different from those of the patch patterns, acquiring colorimetric values for each of said patch patterns from the read-out image data, and adjusting the density of said image formation device based on said density-gradation values and said acquired colorimetric values for each of said patch patterns; said program causing said control device to execute: displaying said read-out image data of said patch sheet; detecting a position of said marker patch; detecting and displaying a region from which the colorimetric values for each of said patch patterns are acquired, based on said position of said marker patch, after the displaying of said read-out image data, and before any operation of a user; and, acquiring the colorimetric values for each of said patch patterns based on said displayed region, after confirmation input by the user of said displayed region, wherein, after said detecting and displaying the region from which the colorimetric values are acquired, said program further causes said control device to execute: displaying a screen for receiving input from the user to modify said displayed region in response to an instruction of the user; and, detecting and displaying again the region, based on the input by said user at said screen displayed, and wherein said screen displayed for receiving input has at least two areas for different display ranges both of which display image data for said patch sheet, and one of said areas displays the enlarged image of the selected range in an other of said areas.