Bookbinding apparatus and bookbinding method

A bookbinding apparatus comprising:

• an inputting unit configured to input a printing job including image data for a plurality of pages;
• a printing unit configured to print images on a plurality of sheets based on the printing job inputted by the inputting unit;
• an accumulating unit configured to accumulate the plurality of the sheets printed by the printing unit as a sheet bundle;
• a bookbinding unit configured to form a bound book using the sheet bundle accumulated by the accumulating unit;
• a counting unit configured to count the number of the sheets accumulated by the accumulating unit;
• a control unit, when an interrupting factor for interrupting the printing is generated, configured to restart the printing, if the number of sheets counted by the counting unit is a first number or less, from the top page of the printing job as well as for restarting the printing, if the number of sheets counted by the counting unit is a second number or more, from the page associated with the interrupting factor;
• and
• a selecting unit, when the interrupting factor is generated and if the number of sheets counted by the counting unit is larger than the first number as well as smaller than the second number, configured to select a priority, upon restarting the printing, between the use of the sheet bundle accumulated by the accumulating unit for forming a bound book and no use of the sheet bundle, wherein when the interrupting factor is generated, the control unit restarts the printing, if the number of sheets counted by the counting unit is larger than the first number as well as smaller than the second number and when the selecting unit selects the use of the sheet bundle, from the page associated with the interrupting factor, and when the selecting unit selects no use of the sheet bundle, the control unit allows the printing unit to restart the printing from the top page of the printing job.