METHODS: Four dry pigments of contrasting colour were tested to establish if a relationship existed between the digital colour sample and the base colour. Pigments were then added to a room temperature vulcanizing silicone facial prosthetic material (Cosmesil). Samples were photographed using a digital camera in a sealed box under controlled lighting. The Adobe Photoshop processing package was used to provide histograms of the selected range across the red, green and blue values. A predicted trend was formulated that fitted the observed data as closely as possible.
RESULTS: The variance of the images was used as the means of determining their consistency. For the dry pigments, the results correlated well with one another and all data in the red, green and blue sets followed a similar trend. The silicone samples followed the trends predicted by the dry pigments. Variance in the data was required to be as low as possible if the camera was to be of use in colour matching. The results from this project found variance values of 0.69, 0.29 and 0.25 for the blue, red and green ranges respectively.
CONCLUSION: The variance values for the silicone samples were higher than those for the dry pigments; however all were within an acceptable range for the limits of the human eye and for colour matching of facial prostheses.