Image reading device and vertical stripe determination method

A vertical stripe determination method implemented in an image reading device that includes a sheet-through reading unit in which a reading unit is fixed and image reading is performed through a reading glass while carrying an original, the vertical stripe determination method comprising:

• determining whether or not a read image obtained by the sheet-through reading unit includes a vertical stripe which represents linear images continuous in an original carrying direction;
• determining, when a vertical stripe is formed, matching/mismatching of positions of the vertical stripe in read images obtained before and after moving the reading glass in a direction orthogonal to the original carrying direction;
• determining, based on determination indicating mismatching at the vertical-stripe-position-determining, that a causing matter of the vertical stripe is present on the reading glass and determining, based on determination indicating matching at the vertical-stripe-position-determining, that a causing matter of the vertical stripe is present on a portion other than the reading glass;
• and
• determining a type of the causing matter.

A non-transitory computer readable medium embodying programmed instructions which, when executed by a processor, are operable for performing a method for an image reading device that includes a sheet-through reading unit in which a reading unit is fixed and image reading is performed through a reading glass while carrying an original, the method comprising:

• determining whether or not a read image obtained by the sheet-through reading unit includes a vertical stripe which represents linear images continuous in an original carrying direction;
• determining, when a vertical stripe is formed, matching/mismatching of positions of the vertical stripe in read images obtained before and after moving the reading glass in a direction orthogonal to the original carrying direction;
• determining, based on determination indicating mismatching at the vertical-stripe-position-determining, that a causing matter of the vertical stripe is present on the reading glass and determining, based on determination indicating matching at the vertical-stripe-position-determining, that a causing matter of the vertical stripe is present on a portion other than the reading glass;
• and
• determining a type of the causing matter.