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Pasivní metody detekce obrazových falzifikátů
Saic, Stanislav ; Mahdian, Babak
In today’s digital age, it is possible to effortlessly create image forgeries without leaving any obvious traces of tampering. In this paper we bring a brief review of existing blind methods for detecting image fakery. Blind methods are regarded as a new direction and work without using any prior information about the image being investigated or its source.
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Periodické vlastnosti převzorkovaných obrazů
Mahdian, Babak ; Saic, Stanislav
In recent years, due to the advent of high-performance commodity hardware and improved human computer interfaces, it has become relatively easy to create fake images. Modern, image processing software enables forgeries that are undetectable by the naked eye. Typically, to create high quality and consistent forgeries, several types of tampering techniques are employed simultaneously. One of the most often used techniques is resampling. When two or more images are spliced together, in order to create a consistent tampering, almost always geometric transformations such as scaling or rotation are needed. In this work we propose an effective method to automatically detect resampled portion of images. Generally, resampling is based on an interpolation procedure. We study specific periodic properties presence in interpolated signals and use this for our detection method. We demonstrate our results on several examples.
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Skyté periodicity v interpolovaných signálech a jejich derivacích
Saic, Stanislav ; Mahdian, Babak
Many applications like, texture analysis, image registration, etc., are based on interpolation. Therefore, without the detailed knowledge of how the statistics of the signal is changed by the interpolation process, applications based on statistical approaches working with interpolated signals or with their derivatives can yield miscalculations and unexpected results. Therefore a detailed knowledge about the changes brought into the signal by interpolation could be critical. Sometimes, there exists a need to examine whether a signal has been interpolated.
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