1. An image display apparatus comprising: a display unit configured to display an image; a readout unit configured to selectively read out one of a RAW image and a first developed image obtained by performing a developing process and a compression process for the RAW image, as a candidate image to be displayed following a currently displayed image, from a storage medium storing the RAW image and the first developed image, in accordance with the currently displayed image; a developing unit configured to perform a developing process for the RAW image read out by said readout unit with higher image quality than the first developed image; a decompression unit configured to perform a decompression process for the developed image read out by said readout unit; a storage unit configured to store the candidate image which is processed by said developing unit or said decompression unit so as to be displayed on said display unit; and a control unit configured to perform control to display the candidate image stored in said storage unit on said display unit by switching from the currently displayed image to the candidate image, in response to an instruction to switch an image displayed on said display unit, wherein said readout unit further configured to selectively read out one of the RAW image and the first developed image obtained by performing the developing process and the compression process for the RAW image, in accordance with image quality of the currently displayed image.