1. An image capturing apparatus comprising: an image capturing unit configured to capture an image of a subject by using an image sensor having pixels each including a plurality of areas, and to generate a RAW image for each of the plurality of areas from a signal generated by the image sensor; a generating unit configured to generate a first RAW image and a second RAW image from the RAW images each generated for each of the plurality of areas; a first development unit configured to generate first image data by performing development processing on the first RAW image; a RAW compressing unit configured to generate first RAW image data and second RAW image data by compressing the first RAW image and the second RAW image; and a second development unit configured to perform development processing on the first RAW image, the development processing performed by the second development unit having a higher processing load than the development processing performed by the first development unit, wherein the second development unit generates second image data by performing development processing on the first RAW image by using the second RAW image.