| 摘要 |
The invention relates to a system and method for identifying a photographic camera model from a photograph taking the form of a compressed image that has undergone post-acquisition processing and fulfilling a linear relationship between the expectation and the variance of the pixels, such that σ2ym,n= aµym,n+ b. The system is characterised in that it comprises an image processing device that can supply an analytical relationship between parameters (α, ß ) from the model of the discrete cosine transform (DCT) coefficients and the parameters (a, b) of the camera in the form (I), such that the parameters (c, d) determine fingerprints that characterise a photographic camera model and depend on both the frequency (p, q) and parameters a and b. The system also comprises a device for carrying out statistical hypothesis tests on the DCT coefficients and a statistical analysis device for determining if the photograph was taken by the photographic camera model or by another photographic camera model. The statistical properties of these tests have been established, allowing error probabilities to be controlled a priori. These results can be used, in particular, to guarantee compliance with a constraint on the probability of one of the two possible errors in the test (false positive or false negative). The invention further relates to the use of the method and to the application thereof. |
