There is disclosed an image processing method for generating a mosaic of images. The method includes selecting a cover image from a plurality of images and dividing the cover image into a number of grid blocks. For each grid block, the average color (or other parameter) is calculated and each grid block is assigned a sub-content based on the color matching. Mosaic generation information is transmitted to a server, the mosaic generation information including a list of sub-content to be displayed in the mosaic, each sub-content including corresponding grid block location information. A server verifies whether each of the sub-content exists on the server and transmits sub-content not present on the server, to the server. The mosaic is displayed on a display of a portable terminal the sub-content using the mosaic generation information so that the cover image is reproduced to form of a mosaic of sub-content that represents the cover image and each sub-content includes additional information specific to each sub-content.