1. An image processing device comprising: a processor configured to perform: acquiring input image data representing an input image having a plurality of objects; identifying a plurality of object regions in the input image, the plurality of object regions representing respectively the plurality of objects; generating a mask image using sharpness adjustment degrees that are set for the plurality of object regions respectively; generating output image data by performing an unsharp masking process on the input image by using the mask image, the unsharp masking process being performed so as to adjust sharpness of the input image; and sending the output image data to a printing unit.