1. A wide dynamic range image capturing apparatus comprising: an image capturing device for capturing image data having an electric charge accumulation period varying every frame; a preprocess block for performing DC adjustment, gain adjustment, and gamma characteristics adjustment with respect to the image data; a single shared data storage memory for storing the image data; a memory control block for controlling a write or read operation of the image data with respect to the single shared data storage memory; an image combining block for performing a combining operation process with respect to two frames of image data having the different electric charge accumulation periods to generate combined image data; and an image processing block for performing video signal processing with respect to the combined image data, wherein the memory control block performs in parallel a process of writing a current frame of image data captured by the image capturing device into the single shared data storage memory, a process of reading a previous frame of image data stored in the single shared data storage memory, and a process of writing the combined image data generated in the image combining block into the single shared data storage memory; the image capturing device successively outputs image data having an electric charge accumulation period varying every frame, where two frames constitute one cycle, and the memory control block performs in parallel a process of writing the current frame of the image data captured by the image capturing device into the single shared data storage memory during a frame period, a process of reading the previous frame of the image data stored in the single shared data storage memory during the frame period, and a process of writing the combined image data generated in the image combining block into the single shared data storage memory every frame.