1. An image capturing apparatus comprising: a display unit configured to display an image obtained from an image capturing unit, wherein the image capturing unit is capable of acquiring multi-viewpoint images which are a plurality of two-dimensional images with different viewpoints; at least one processor; and one or more memories storing instructions that, when executed by the at least one processor, cause the image capturing apparatus to: derive a disparity amount of the multi-viewpoint images in relation to a subject; specify, as a focus area, a partial subject area focused in an input two-dimensional image related to the multi-viewpoint images based on the derived disparity amount to generate focus area data that represent whether or not each pixel is included in the focus area; apply an edge detection filter to the focus area data so as to generate a boundary image indicating a boundary between the focus area and an area other than the focus area in the input image; and generate a display image that represents the specified focus area in a manner different from an area other than the focus area by using the input image and the boundary image.