Image reading apparatus and image forming apparatus

An image reading apparatus comprising:

• a first guide member and a second guide member fixed and opposed to each other to form a document feed path, the first guide member being made of a transparent material, the second guide member comprising a shading correction white reference member;
• an image read section for illuminating light through the first guide member to the second guide member and generating image data from reflected light;
• and
• a control section for performing a stain presence determination of whether shading correction image data generated by the image read section reading the image of the white reference member is affected by a stain attached to the first guide member or the second guide member, a stain location determination that determines, when it is determined that the image data is affected by the stain, to which of the first guide member and the second guide member the stain is attached according to a tone value variation in a portion of the shading correction image data that corresponds to the stain edge, the variation being along a predetermined distance in the main scanning direction, and a handling process for handling the stain on the first guide member or the second guide member according to the stain location determination, wherein
• the control section determines in the stain location determination that a stain is attached to the first guide member if an absolute value of the variation is not more than a threshold for the stain location determination and that a stain is attached to the second guide member if the absolute value of the variation is more than the threshold for the stain location determination.