1. A processing apparatus comprising: a receiving unit configured to receive an image data group; a specifying unit configured to specify an object included in each image based on image data in the image data group received by the receiving unit; a grouping unit configured to generate a group by grouping objects correlating with each other; an acquisition unit configured to acquire first object information specifying a first object; a setting unit configured to set correlation information specifying a correlated object having a correlation with the first object, based on the first object information acquired by the acquisition unit and group information of the group generated by the grouping unit; and, an extraction unit configured to extract image data including the first object and image data including the correlated object from the image data group based on the first object information acquired by the acquisition unit and the correlation information set by the setting unit.