Image reading apparatus

An image reading apparatus comprising:

• a first white memory;
• a second white memory including a nonvolatile memory;
• an image reading device having multiple resolution modes to acquire an image data with a resolution mode of one of the multiple resolution modes;
• circuitry configured to:
• process signals of the image data;
• determine whether the image data is one of:
• first white shading data as a reference, the first white shading data having a number of resolution modes smaller than a number of the multiple resolution modes of the image reading device;
• or
• the image data acquired from an original document read by the image reading device;
• temporarily store the first white shading data in the first white memory;
• store the first white shading data stored in the first white memory in the second white memory;
• convert a resolution of the first white shading data stored in the second white memory according to a resolution of the image data to create second white shading data;
• store the second white shading data in the first white memory;
• and
• correct the image data by the second white shading data.