Color Measurements with a Consumer Digital Camera Using Spectral Estimation Techniques

The use of spectrophotometers for color measurements on printed substrates is widely spread among paper producers as well as within the printing industry. Spectrophotometer measurements are precise, but timeconsuming procedures and faster methods are desirable. The rapid development of digital cameras has opened the possibility to use consumer digital cameras as substitutes for spectrophotometers for certain applications such as production control. Two methods for estimating the reflectance properties of objects from camera RGB measurements using linear estimation techniques combined with linear and non-linear constraints are presented. In the experiments, we have investigated if these techniques can be used to measure the reflectance properties of flat objects such as printed pages of paper. Reflectances were converted to CIELAB color values, and the minimization of color errors were evaluated with CIE color difference formulas. Our experiments show that a consumer digital camera can be used as a fast and inexpensive alternative to spectrophotometers for color measurements on printed substrates.