A color changing lighting device incorporating a plurality of led emitters having a plurality of colors each emitting a distinct color of light upon being energized by a power supply. A relational database may include a plurality of first type data items and associated second type data items. It also can have a relatively large tip angle which preferably terminates at a relatively sharp termination point. Based on the device identifier, the digital signage server selects particular digital signage items for display on the particular printing device. A p-type TFT has a structure having no LDD region. The method includes generating an electronic signature to be affixed to image data, and generating control information used for controlling an action for the image data based on a result of verification of the electronic signature.