Image reading device, image forming apparatus therewith, and image reading method

An image reading device, comprising:

• a contact glass which is fixed on a top face of a scanner frame and which is partitioned into a manual placement document glass and an automatic reading glass;
• a document conveying device which is supported openably and closably in an up-down direction with respect to the contact glass and which conveys a document to a top face of the automatic reading glass;
• a reading module which is arranged below the contact glass so as to be reciprocatable in a sub scanning direction and which is configured to read image data of the document by a fixed-document method where an image of the document placed on the manual placement document glass is read while the reading module moves in the sub scanning direction and by a sheet-through method where the image of the document conveyed on the top face of the automatic reading glass by the document conveying device is read while the reading module stays at an image reading position facing the automatic reading glass;
• and
• a control portion which controls reading operation by the reading module,
• wherein
• the control portion includes
• a reading processing portion which is configured to perform fixed-reading processing where the image data is read by the fixed-document method using the reading module and conveyed-reading processing where the image data is read by the sheet-through method using the reading module,
• a correction processing portion which performs shading correction using a first adjustment value on the image data read through the fixed-reading processing and which performs the shading correction using a second adjustment value on the image data read through the conveyed-reading processing, and
• a setting processing portion which acquires the first adjustment value based on data of a reference image acquired through the fixed-reading processing and which acquires the second adjustment value based on data of the reference image acquired through the conveyed-reading processing in the reading processing portion,
• the conveyed-reading processing can be performed while the reading module is kept staying at any of a plurality of the image reading positions including a reference reading position, and
• the setting processing portion, when a reference second adjustment value which is the second adjustment value at the reference reading position is acquired, calculates the second adjustment values for the plurality of image reading positions based on the reference second adjustment value, and when the reference second adjustment value is not acquired and the first adjustment value is acquired, calculates the second adjustment values for the plurality of image reading positions based on the first adjustment value.