In an image forming apparatus that employs a laser scanning optical system that does not use an f lens, in the case where magnification correction by insertion/removal of an auxiliary pixel is performed based on the premise of digital PWM, an insertion/removal position of an auxiliary pixel is controlled in accordance with a purpose of each piece of image processing.

In an image forming apparatus that employs a laser scanning optical system that does not use an f lens, in the case where magnification correction by insertion/removal of an auxiliary pixel is performed based on the premise of digital PWM, an insertion/removal position of an auxiliary pixel is controlled in accordance with a purpose of each piece of image processing.

An image bearing member includes an agitation member and a sheet member. A sheet portion of an agitation member comes into contact with a second side surface of the blade member. When viewed from a rotation axis direction of a shaft portion of the agitation member, an imaginary line A connects a position of an end portion on a most upstream side of the second side surface in the rotation direction and an axial center position of the shaft portion, and an imaginary line B is orthogonal to the imaginary line A and passes through the position of the end portion on the most upstream side of the second side surface, and the free end of the sheet member is disposed at a position closer to the blade member than a position where a second line intersects with an outer circumferential surface of the image bearing member.

Scanning optical unit includes: light source; incident optical system including one coupling lens for converting light from the light source into a light beam; optical deflector having a reflecting surface and configured to reflect and deflect the light beam in main scanning direction; and scanning optical system for focusing the deflected light beam on an image surface. The incident optical system converges the light beam on the reflecting surface in sub-scanning direction. Further, 0.01(s/m).sup.20.27 and s2<1 are satisfied, where m is a lateral magnification of the entire optical system from the light source to the image surface in the main scanning direction, s is a lateral magnification of the entire optical system in the sub-scanning direction, and s2 is a lateral magnification of the scanning optical system from the reflecting surface of the optical deflector to the image surface in the sub-scanning direction.