1. A method for browsing a summary still image, the method comprising: tracking a plurality of objects included in an input video image comprising a plurality of image frames, by an image processing engine; selecting a representative image frame of each of the plurality of objects from the plurality of image frames based on a plurality of object selection conditions, by the image processing engine; storing the selected representative image frames of the plurality of objects, by the image processing engine; and generating at least one summary still image by selecting two or more objects from the plurality of objects in a temporal order in which the two or more objects appear in the input video, until a number of the selected two or more objects reaches a maximum number of objects set for a single summary still image, by a browsing engine, wherein the maximum number of objects is set based on a number of the plurality of objects and a degree of overlapping between the plurality of objects, wherein the plurality of object selection conditions are given different score ranges according to a priority set to each of the plurality of object selection conditions, wherein the plurality of object selection conditions comprises a degree of overlapping between the plurality of objects, and wherein the selecting the representative image frame comprises selecting an image frame having a highest sum score for the plurality of object selection conditions as the representative image frame, from among the plurality of image frames.