Abstract: A portable color measuring device is provided that includes a hand-holdable housing. The color measuring device is configured to receive an independently operable processing device that is mounted to the housing. The independently operable processing device is a portable general purpose computer that executes software applications to control the operation of the color measuring device and process color data. The color measuring device measures the color properties of a sample by illuminating the sample with a light source. The measured properties are processed and/or analyzed by the independently operable processing device and results are displayed to a user. Software applications reside on the independently operable processing device allowing software upgrades or modifications to be easily performed. New applications can be downloaded to the processing device or the processing device can be interchanged with a different processing device.