Dust and/or dirt detection in image reading apparatus having read-while-feed function

An image reading apparatus comprising:

• a scanner adapted to read an image of an original;
• a document feeder adapted to feed said original to a platen;
• a dust or dirt detector adapted to detect presence of dust or dirt on said platen;
• an original size detector adapted to detect a size of said original;
• a controller adapted to perform a read-while-feed operation in which an original, while being fed by said document feeder, is read by said scanner placed at one of a plurality of predetermined positions, corresponding to different sizes of originals, on the basis of the size of said original detected by said original size detector, and inhibit the read-while-feed operation to read said original at said one of the plurality of predetermined positions in a case where said dust or dirt detector detects the presence of dust or dirt on said platen at said predetermined position on said platen, wherein said controller turns on a flag indicative of inhibition of the read-while-feed operation upon inhibiting the read-while-feed operation, and turns off the flag upon allowing the read-while-feed operation;
• and
• a flag determination unit for determining on/off of the flag indicative of inhibition of the read-while-feed operation,
• wherein said controller is also adapted to control to perform a stationary reading operation in which the original is held at a fixed position on the platen and read while moving said scanner, and
• wherein said controller controls to perform the stationary reading operation when said flag determination unit determines that the flag is on, and controls to perform the read-while-feed operation when said flag determination unit determines that the flag is off.