Color accuracy of two non-calibrated commercial cameras

Obtaining color coordinates from an image is a complicated process, in which calibration and characterization of the camera are essential. However, it is interesting to study what can be obtained if the camera is not calibrated. This work achieves an approximation to this study. Two different commercial cameras have been employed to obtain images of 8 different color samples. No calibration of the cameras has been performed, recovering CIELAB coordinates of the samples through Adobe® Photoshop® software. The results have been compared with the CIELAB coordinates computed from the spectral radiance of the samples measured with a spectroradiometer. The illumination was controlled putting the samples in a GretagMacbeth boothlight provided with a daylight simulator lamp. In this work the aperture of the cameras was fixed in 5.6. Nevertheless the sensitivity (ISO values) and exposure time have been systematically changed. The results show differences between the cameras, the samples and the setup of sensitivity and exposure time. The average color differences of the samples are 10.83 and 18.79 CIELAB units for the two cameras with the optimal combinations of ISO value and exposure time. This research had been supported by the Egide agency (France) via the Partenariat Hubert Curien Franco-Espagnol (Program Picasso No 19258SF) and by the Ministerio de Ciencia e Innovación (Spain) via the Acción Integrada España-Francia (Program HF2008-0056). Also Research Project FIS2007-64266, Ministerio de Educación y Ciencia (Spain), with ERDF (European Regional Development Fund) support.