1. A method of detecting tampering in a digital image, comprising: mining one or more features of a digital image under scrutiny based on a spatial derivative, wherein mining the one or more features based on the spatial derivative comprises: determining a spatial derivative associated with at least a portion of a digital image under scrutiny; and extracting, based on the spatial derivative, one or more neighboring joint density features and/or marginal features from the digital image; mining one or more features of the digital image using at least one DCT transform, wherein mining one or more features of the digital image by the at least one DCT transform comprises: extracting one or more neighboring joint density features and/or marginal joint density features from the digital image; and determining one or more calibration features in a DCT domain based on the neighboring joint density features and/or marginal joint density features; and detecting tampering in the digital image under scrutiny at least in part by the features mined based on the spatial derivative and at least in part by the features mined using the at least one DCT transform.