Charge-coupled devices can provide an excellent means for the quantification of DNA band images on membranes and photographic film. However, proper consideration must be given to important parameters such as signal-to-noise ratio and resolution, especially in applications which demand the use of large format media. When employed in the direct imaging of chemiluminescent blots, the charge-coupled device can provide equal or better sensitivity than that obtained by indirect methods using film, with the additional advantages of wide dynamic range and freedom from the vagaries of film processing.