In an image forming apparatus, a paper sheet cassette stores a bunch of paper sheets to be fed. A media sensor unit measures a thickness and a surface roughness of one paper sheet fed and transported from the paper sheet cassette. A residual sheet amount sensor detects a residual amount of the paper sheets in the paper sheet cassette. A residual sheet number estimating unit estimates the number of residual paper sheets in the paper sheet cassette on the basis of (a) a thickness of a bunch of the paper sheet in the paper sheet cassette, the thickness of the bunch corresponding to the residual amount detected by the residual sheet amount sensor and (b) the thickness of the one sheet and the surface roughness of the one sheet measured by the media sensor unit.

An image reading system includes a transport section that transports documents one by one from a batch of documents, a reading section that reads documents, a display section that displays a setting screen by which a target condition, which is a condition for a document that is to be a reading target, is set, and a control section, wherein the control section counts the number of documents that matches a target condition based on image data of the documents read by the reading section, and cause the display section to display the number of documents that matches the target condition.

A conveying mechanism sequentially conveys document sheets placed on a document sheet placing portion to a document sheet discharge portion through an image reading position at which an image is read from each of the document sheets. The document sheet discharge portion is provided below the document sheet placing portion. A raising and lowering mechanism raises and lowers the document sheet placing portion. A first determination processing portion determines whether or not any of the document sheets is placed on the document sheet placing portion. A second determination processing portion determines whether or not any of the document sheets is placed on the document sheet discharge portion. A raising and lowering processing portion controls raising and lowering operations by the raising and lowering mechanism on the basis of results of determinations made by the first determination processing portion and the second determination processing portion.