1. An image processing method comprising: generating a plurality of smoothed images obtained by smoothing an original image with a plurality of degrees of smoothing, respectively; generating an illumination image having pixel values of an illumination component of the original image by using the plurality of smoothed images that undergo weighting in which at least one of the smoothed image is assigned a different weight, wherein the weighting is set so that a weight for one of the smoothed images, which is smoothed with a degree of smoothing higher than a predetermined level, is lower when a feature amount indicating a degree of influence of a bright region of the one smoothed image on visibility of the one smoothed image is higher; generating a reflectance image on a basis of the original image and the illumination image, the reflectance image having pixel values of a reflectance component of the original image; and generating a reproduced image at least on a basis of the reflectance image and degree-of-enhancement information indicating a degree of enhancement of the reflectance component of the original image, the reproduced image being reproduced to enhance visibility of the original image.