A film flattening apparatus and method of operation for a printer particularly operable in a film flattening mode for flattening image frames of filmstrip segments attached by a side attached tow web and transported through a transport path gap between the flattening apparatus and an aperture formed in a stationary film transport base. The flattening apparatus is formed of first and second clamping members suspended apart from the base in a retracted position during the web transport and moved toward the base to a contact position pressing against the longitudinal or lateral and the transverse edges of the filmstrip image frame in a film flattening mode. The first and second clamping members are formed with longitudinally and transversely extending clamping elements, respectively and are suspended apart from one another and the base in the retracted position and advance sequentially in a nested relation toward the base and the contact position in the film flattening mode. In the film transport mode, the longitudinally extending clamping elements guide against the filmstrip lateral edges and tend to flatten excessively, transversely curled filmstrip segments. The transversely extending clamping elements are positioned further apart in the transport mode and out of interference with the filmstrip segment leading ends transversely curled centrally toward the second clamping member. Preferably, the base has a thickness within which sculpted, arcuate reliefs are formed centered on the mid-point of the transverse opening edges of the aperture and provide upward guidance to filmstrip leading ends transversely curled centrally toward the aperture in the base.