An image forming device comprising: a license accepting means for accepting assignment of a license; a switching means for switching a system speed when the assignment of the license has been accepted by said license accepting means; a storing means for storing information indicating that the system speed has been switched when the system speed has been switched by said switching means; a switch determination means for determining whether or not the information indicating that the system speed has been switched is stored in said storing means; a first image stabilization means for performing two-stage image stabilization when it is determined by said switch determination means that the information is stored, the two-stage image stabilization being a process for determining a setting value of a parameter relating to an image formation process of the image forming device; and a second image stabilization means for performing single-stage image stabilization when it is determined by said switch determination means that the information is not stored, the single-stage image stabilization being a process for determining said setting value, wherein in said two-stage image stabilization, a provisional setting value of said parameter is determined within a first adjustable range based on sampling images formed using a plurality of values of said parameter that are different from each other and within said first adjustable range, and said setting value is determined within a second adjustable range narrower than said first adjustable range and including said provisional setting value based on sampling images formed using a plurality of values of said parameter that are different from each other and within said second adjustable range, and in said single-stage image stabilization, said setting value is determined within a third adjustable range including an already determined setting value based on sampling images formed using a plurality of values of said parameter that are different from each other and within said third adjustable range. a license accepting means for accepting assignment of a license; a switching means for switching a system speed when the assignment of the license has been accepted by said license accepting means; a storing means for storing information indicating that the system speed has been switched when the system speed has been switched by said switching means; a switch determination means for determining whether or not the information indicating that the system speed has been switched is stored in said storing means; a first image stabilization means for performing two-stage image stabilization when it is determined by said switch determination means that the information is stored, the two-stage image stabilization being a process for determining a setting value of a parameter relating to an image formation process of the image forming device; and a second image stabilization means for performing single-stage image stabilization when it is determined by said switch determination means that the information is not stored, the single-stage image stabilization being a process for determining said setting value, wherein in said two-stage image stabilization, a provisional setting value of said parameter is determined within a first adjustable range based on sampling images formed using a plurality of values of said parameter that are different from each other and within said first adjustable range, and said setting value is determined within a second adjustable range narrower than said first adjustable range and including said provisional setting value based on sampling images formed using a plurality of values of said parameter that are different from each other and within said second adjustable range, and in said single-stage image stabilization, said setting value is determined within a third adjustable range including an already determined setting value based on sampling images formed using a plurality of values of said parameter that are different from each other and within said third adjustable range.