Image Number 5 for United States Patent #6668144.
An image forming apparatus that detects a type of recording sheet and sets an image forming condition in accordance with the detected type of sheet includes a feeding unit that feeds a sheet, an image forming unit that forms an image on a sheet, and a reading unit that reads a picture of a surface of a sheet. A discriminating unit discriminates whether re-reading is necessary, on the basis of the picture. If so, another unit changes a reading condition of the reading unit and causes the reading unit to re-read the picture of the surface of the sheet. A detecting unit detects a type of sheet on the basis of the picture read by the reading unit, and a controlling unit controls an image forming condition on the basis of the result of the detection.