1. An image processing device comprising: a processor configured to execute a process including extracting a pixel value of each of a plurality of areas of a same color that are arranged at different positions on a color chart that is captured in an image, and specifying by using the extracted pixel values of the areas and arrangement positions of the areas of the same color an area that has a pixel value that corresponds to a function that expresses fluctuation of pixel values according to a position due to non-uniformity of an illumination environment that fluctuates the pixel values at a constant rate in one direction, and correcting a pixel value of a correction target area between the areas of the same color according to the pixel value of the specified area.