Document size detection apparatus

摘要

A driving unit drives an illuminating light (232). An image pick-up device (207) reads a document in a main-scanning direction. An optical unit projects an image of the document onto the image pick-up device (207). An extracting unit extracts image signals at a plurality of points in the main-scanning direction of a first position and a second position in a sub-scanning direction. A document detecting unit creates binary data indicating a presence of the document at each of the points based on the image signals extracted. A size detecting unit determines a size of the document in the main-scanning direction based on a distribution of presence and absence of the document.