Patent ID: 8248638

Claim:
An image forming device capable of forming index images that correspond to a plurality of files, respectively, onto a recording medium, comprising: an image data generating unit configured to generate one of first image data and second image data as data for forming the index image corresponding to each of the plurality of files; a file selecting unit configured to select, from the plurality of files, files which comprise at least one parameter other than image data; a parameter detecting unit configured to detect the at least one parameter for each of the files selected by the file selecting unit; a parameter judging unit configured to judge whether the at least one parameter detected by the parameter detecting unit satisfies a predetermined condition; and a control unit configured to control the image data generating unit to generate one of the first image data and the second image data based on the judgment by the parameter judging unit, wherein the control unit is configured to control the image data generating unit to generate the second image data, when the parameter judging unit judges that the at least one parameter detected by the parameter detecting unit satisfies the predetermined condition, and to generate the first image data, when the parameter judging unit judges that the at least one parameter detected by the parameter detecting unit does not satisfy the predetermined condition, wherein the parameter detecting unit includes a time measuring unit configured to measure a time period taken for the data generation by the image data generating unit for each of the selected files, wherein the parameter judging unit is configured to judge, for each of the selected files, whether the time period measured by the time measuring unit is more than a predetermined time period, and wherein the control unit is configured to control the image data generating unit to generate the second image data for each file for which the parameter judging unit judges that the time period is more than the predetermined time period.