1. An image sensor comprising: an imaging unit including a plurality of photoelectric converters; an input unit, including a terminal, to which compressed image data is input from outside of the image sensor; an image processor that applies image processing to image pickup data obtained from the imaging unit; and a decompressor for extracting metadata attached to the compressed image data by analyzing a data structure of the compressed image data, decompressing the compressed image data input from the input unit, and supplying the decompressed image data and the extracted metadata to the image processor, wherein the image processor applies the image processing to the decompressed image data using the metadata.