Abstract: A rotation drive unit having a first reduction mechanism of traction transmission system comprising a drive roller attached to a drive shaft and a driven roller attached to a driven shaft, and a second reduction mechanism of gear transmission system comprising a drive gear attached to the drive shaft and a driven gear attached to the driven shaft. The first reduction mechanism generates a braking effort while making slippage between the rollers during transmission of a rotational driving force from the drive shaft, and exerts a torque load on the second reduction mechanism of the gear transmission system. Since this unit transmits the rotational driving force via the first reduction mechanism while exerting the load upon the second reduction mechanism, it provides a satisfactory and reliable speed-reducing function as well as reliable and accurate transmission of the rotational driving force even if equipped with a plurality of driven shafts coupled to the single drive shaft.

Abstract: An image lens distortion correcting method having step (A) for printing an arbitrary image I1 in a computer; step (B) for photographing the printed image I1 with a camera having a lens distortion and obtaining a photographed image I2 in the computer; step (C) for obtaining a parameter &thgr; such that the image I1 is artificially distorted with the parameter &thgr; and an obtained distorted image I1ud equals with the photographed image 2; and step (D) for using the obtained parameter &thgr; to correct the image photographed by the camera. Thereby, (1) no correspondence point needs to be given, (2) no special tool or object is used, and (3) all points on the image are used, so that an internal parameter can automatically be obtained with high precision, and image lens distortion can be corrected with high precision.

Abstract: There is disclosed an image lens distortion correcting method comprising: an image printing step (A) for printing an arbitrary image I1 in a computer; an image pickup step (B) for photographing the printed image I1 with a camera having a lens distortion and obtaining a photographed image I2 in the computer; a parameter estimating step (C) for obtaining a parameter &thgr; such that the image I1 is artificially distorted with the parameter &thgr; and an obtained distorted image I1ud equals with the photographed image I2; and an image correcting step (D) for using the obtained parameter &thgr; to correct the image photographed by the camera. Thereby, (1) no correspondence point needs to be given, (2) any special tool or object is not used, and (3) all points on the image are used, so that an internal parameter can automatically be obtained with high precision, and an image lens distortion can be corrected with high precision.