16. An image reader, comprising: an automatic document feeder having a document inlet through which a document enters the automatic document feeder, a document outlet through which the document exits the automatic document feeder and a document transfer channel along which the document moves from the document inlet to the document outlet, the document transfer channel including a document reading portion; and a reading unit arranged adjacent the document reading portion of the document transfer channel and configured to receive light reflected from the document positioned at the document reading portion, wherein the document reading portion of the document transfer channel has a component having a surface tension that is less than or equal to about 40 dyne-per-centimeter, wherein the component of the document reading portion has a surface roughness (Ra) of about 0.3 microns (μm) to about 30 μm.
16. An image reader, comprising: an automatic document feeder having a document inlet through which a document enters the automatic document feeder, a document outlet through which the document exits the automatic document feeder and a document transfer channel along which the document moves from the document inlet to the document outlet, the document transfer channel including a document reading portion; and a reading unit arranged adjacent the document reading portion of the document transfer channel and configured to receive light reflected from the document positioned at the document reading portion, wherein the document reading portion of the document transfer channel has a component having a surface tension that is less than or equal to about 40 dyne-per-centimeter, wherein the component of the document reading portion has a surface roughness (Ra) of about 0.3 microns (μm) to about 30 μm. 17. The image reader according to claim 16 , wherein the component comprises an automatic document feeder window configured to allow passage of the light reflected from the document to the reading unit.