Abstract: A compact vertical plate processor providing dwell time, brushing and squeegee for developing plates which are inserted vertically from the top of the processor between pairs of transport rollers and brush rollers and thereby immersed in a developing solution. A spring-loaded cam lever mechanism separates each pair of upper and lower transport rollers as well as an intermediate pair of brush rollers from a contacting position to a loading position to permit insertion of a plate into the solution. After a pre-set dwelling time, a drive motor is activated for rotating the rollers to deliver the plate up out of the processor. Also, an adjustable plate size adapter sets the height at which the plate can be lowered into the tank so that such plate never falls from between the nip of the lowest set of rollers in the processor. The processor provides automatic developing of the plate in a vertical, non-feedthrough operation, thereby permitting a compact apparatus requiring a minimum of table top space.