Abstract: A discrete cosine transform circuit including a shuffle circuit with n (n is an integer) shuffle stages, the n shuffle stages sequentially having 2.sup.n, 2.sup.n-1, . . . , 2.sup.1 input/output stages in such a manner that a first one of the n shuffle stages has the 2.sup.n input/output stages and a nth one of the n shuffle stages has the 2.sup.1 input/output stages, the nth shuffle stage including first and second RACs for performing a discrete cosine transform using a distributed arithmetic process, the first RAC having 2.sup.n-2 input/output stages, the second RAC having 2.sup.n-1 input/output stages. A path switching section is connected to the input stages of the shuffle circuit for changing a transfer path of output information from the output stages of the shuffle circuit according to whether the discrete cosine transform to be processed is a forward discrete cosine transform or an inverse discrete cosine transform.

Abstract: An image projection system having a built-in mechanism for changing unframed transparencies comprises a frame, a source of illumination, a projection lens, a stage mounted to the frame for positioning a transparency thereon for view, delivery means for gripping and slidingly moving an unframed transparency along the surface of said stage, a magazine holding a stack of unframed transparencies for insertion into the frame adjacent to said stage, feed means for feeding the uppermost transparency from a stack of transparencies in the inserted magazine, and suitable drive means. A second magazine and second feed means can be included in the system for bedirectional changing of unframed transparencies. An electrical logic circuit interfacing with a control module can be included in the system for control. The mechanism for changing unframed transparencies can be isolated and built in a detached unit for use with a conventional image projector which does not have such a built-in mechanism.