1. An image processing device for processing image data indicative of an image to be printed by a print execution section, the print execution section having a print head that is reciprocated in a main scanning direction and that is capable of printing a partial image in a unit printing area for each main scan, the image processing device comprising: a process section configured to execute an image process on image data so as to generate processed image data; a generation section configured to execute a halftone process on the processed image data so as to generate print data; and a supply section configured to supply the print data to the print execution section; the process section comprising: a color conversion section configured to convert the image data, expressed in gradation values for a plurality of first color components defined in a first color system, into converted image data, expressed in gradation values for a plurality of second color components, the plurality of second color components being defined in a second color system and corresponding to a plurality of ink colors used in printing; an index value determination section configured to determine an index value for each of a plurality of target pixels included in edge image data, the index value for each target pixel being related to density of the target pixel, wherein the edge image data corresponds to an edge portion of a unit printing area and is part of partial image data within the image data, and the partial image data corresponds to the unit printing area, the index value determination section being further configured to determine the index value of the target pixel based on gradation values for the plurality of second color components that serve as the pixel value of the target pixel; and an adjustment section configured not to adjust a pixel value of the target pixel in a first case where the density of the target pixel is determined to be relatively low based on the index value of the target pixel, and configured to adjust the pixel value of the target pixel so as to reduce the density of the target pixel in a second case where the density of the target pixel is determined to be relatively high based on the index value of the target pixel, the adjustment section being further configured, in the second case, to adjust the gradation value for at least one of the plurality of second color components in the target pixel so that the index value of the target pixel is adjusted to a target value, and the adjustment section being further configured, in the second case, not to adjust a gradation value for a second color component in the target pixel with respect to pigment ink, but to adjust a gradation value for a second color component with respect to dye-based ink.