A method of image processing includes: reading a data file in a predetermined page description language including a search key; chaining a plurality of pieces of resource data in each of a plurality of resource dictionaries; loading the chained plurality of pieces of resource data in each of the plurality of resource dictionaries in a memory area including unique keys; searching the requested resource data from the chained pieces of resource data using the search key for matching the unique key of the requested resource data one by one along the chain in both direction from a starting piece of resource data; labeling each of the plurality of pieces of resource data based on a history of the matching. The searching includes determining the starting piece of resource data in the chained plurality of pieces of resource data based on the history.