White balance correction for detection of holograms in color images of black and white photographs

Taking a photo or video of a user's identification document is one of the ways to comply with the law when you use mobile services. It is designed to reduce the number of illegal actions. An element of protection against malefactor attacks on providing the original document is the detection and recognition of optically variable document security elements. 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, we considered the possibility of using prior information about color consistency of the document area to compensate distortion of the white balance on the 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 protective film with optically variable devices. The method is tested on a real data obtained with a mobile device.