White Balance Correction for Detecting Holograms in Color Images of Black-and-White Photographs

The key feature of optically variable elements is the appearance and disappearance of high saturation colors during shooting under different angles. The accuracy of color saturation measurement algorithms is limited by the automatic white balance correction subsystem, which uncontrollably changes the color characteristics of the image from frame to frame. In this paper, the possibility of using a priori information about color consistency of the document area to compensate for distortion of the white balance is considered using examples of document owner monochrome photographs. The proposed method of color correction increases the contrast of color saturation between the unprotected areas of the photograph and the areas covered by visually variable image on the protective film. The method is tested on reference data obtained with a mobile device.