1. A lesion evaluation information generator comprising: an image data acquirer configured to acquire endoscopic color image data that represents an endoscopic image showing a lesion; a memory; and a processor configured to, when executing processor-executable instructions stored in the memory, provide: a color information determiner configured to determine a hue value and a saturation value of each of pixels included in the endoscopic image based on the acquired endoscopic color image data; a correlation value determiner configured to determine, for at least a part of the pixels of the endoscopic image, a correlation value that represents a correlation between color information of each individual pixel and reference color data, based on: a hue correlation value that represents a correlation between the determined hue value of each individual pixel and a reference hue value of the reference color data; and a saturation correlation value that represents a correlation between the determined saturation value of each individual pixel and a reference saturation value of the reference color data; and an evaluation value generator configured to generate an evaluation value for evaluating a severity of the lesion in the endoscopic image, by deriving a summation of the correlation values from integrating the correlation value determined for each individual pixel.