Abstract: In each of two images obtained by a digital radiography system, for example, a mask image and a live image, two regions of interest are set by a cutout position setting section. Images within corresponding regions of interest are subjected to subtraction in a subtraction processing section. By calculating the entropy of one of two subtraction images in an entropy calculating section, amounts of shift to make the entropy local minimum is searched for. By using the amounts of shift to make the entropy local minimum, an amount of rotation is searched for, which makes the entropy of the other subtraction image local minimum. The amounts of shift and rotation are set by a parameter setting section in accordance with the calculated entropy.

Abstract: A device for containing a radiation recording medium includes an opening through which the recording medium is placed and a light shutting plate for closing the opening to prevent light from penetrating into the casing. A light shutting plate is provided integral with a handle. A locking mechanism is provided for bringing a casing into locking engagement with the light shutting plate. Since the device is moved by holding the handle with the light shutting plate locked on the casing, there is no possibility that the film will be inadvertently exposed to light with the shutter plate left unclosed.