A look-up table generating method generates a look-up table by synthesizing at least first and second look-up tables to indicate first and second output characteristics for first and second region. The first output characteristic includes an output characteristic in which a first color difference between color values of the first and second color materials under a first observation light source is within a first range for all of the first region, and a second color difference between color values of the first and second color materials under a second observation light source is outside a second range for at least part of the first region. The second output characteristic includes an output characteristic in which the first color difference is outside the first range for at least part of the second region, and the second color difference is within the second range for all of the second region.