| 摘要 |
The present invention is related to a system for the authentication of digital images captured by a digital camera, a scanner or any other image-acquisition method, which is intended to avoid damages caused by the use and/or spread of the altered images. Said system uses watermark techniques able to locate and recover the altered areas. In this system, the watermark is generated by binarizing the original image using the halftoning technique. The watermark signal is inserted into the domain of the two-dimensional DCT in an unnoticeable manner, obtaining approximately 40 [dB] of the PSNR of the marked image with regard to the original image. The detection of the altered areas is performed by the comparison between the watermark signal extracted and the signal obtained from the image under analysis, obtaining an error of false negative lower than 10-4 and approximately 2.5 x 10-4 of error of false positive. Once the altered areas are detected, these being recovered by introducing the co rresponding watermark signal to the altered areas to the previously trained neuronal network. This process allows the altered areas to be recovered with an improved visual quality, obtaining 35 [dBl] as a PSNR average of the recovered areas with regard to the original areas. |
