1. An image processing apparatus, comprising: a display control unit configured to display on a display apparatus a composite image comprising a plurality of images, such that, in a transition period of the display, the composite image is displayed as being changed over time to include a further image and, in a stable period of the display, all of the plurality of images in the composite image are displayed as not being changed to include further images; a receiving unit configured to receive an output command while the composite image is being displayed on the display in either the stable period or the transition period, wherein the output command is a command to display the composite image on the display apparatus as a print candidate image; a determination unit configured to determine, when the output command has been received, whether the output command received by said receiving unit was received during the stable period or during the transition period and, if said receiving unit received the output command during the stable period, to determine the composite image being displayed and the plurality of images included in the composite image as the only print candidate images or, if said receiving unit received the output command during the transition period, to determine the composite image that was displayed in the last stable period, the composite image that will be displayed in the next stable period and the plurality of images included in the two composite images as the only print candidate images; a selection unit configured to display the print candidate images by said determination unit on the display apparatus and to select an image for outputting from among the displayed print candidate images; and an output unit configured to output the selected print candidate image to a printer.