Farmers do not typically have ready access to sophisticated color measurement equipment. The idea that farmers could use their smartphones to determine when and if crops are ready for harvest was the driving force behind this project. If famers could use their smartphones to image their crops, in this case tomatoes, to determine their ripeness and readiness for harvest their farming practices could be simplified. Five smartphone devices were used to image tomatoes at different stages of ripeness. A relationship was found to exist between the hue angles taken from the smartphone images and as measured by a spectroradiometer. Additionally, a tomato color checker was created using the spectroradiometer measurements. It is intended to be made of a material that makes it easy to transport into the field. The chart is intended for use in camera calibration for future imaging. Different cloth materials were tested, with the eventual choice being a canvas material with black felt backing. Other possibilities are being investigated. The results from the smartphones and the charts will be used in further research on the application of color science in agriculture. Other possible future applications include monitoring progress relative to irrigation and fertilization programs and detection of pests and disease.