Image Processing Reference
In-Depth Information
Widening of digital audio and videorecording devices distribution and an abrupt increase of
storage density had led to situation where the most frequently identification case is
identifiable records that are external to identifiable device, leading to complete absence of
the primary physical state of the primary “source” and file system properties. Than the rest
identification way are the identification based on file format features and identification
based on features of recording path and postprocessing.
Copyright protection task operates with the same features, but the signal can be presented
after multiple format conversions, which preserve consumption quality but changes the
physical representation of original signal, so the identifiable and applicable features are ones
containing in digital content rather than format representation.
Currently questions of identification of analog audio, still images and video recording
devices are well researched and are based on traces which the recording device leaves on
the carrier in process of writing at change of its physical properties. It is widely used at any
carrying out of the expertizes which example is, in particular, phototechnical examination.
Phototechnical expert appraisal represents judicial expertize on research of facsimiles of
various property and the content, photos (including numeral), paper pictures (photo), for
definite purposes of criminal, civil or arbitration legal proceedings. Each picture contains
information about the circumstances concerning procedure of manufacturing.
Phototechnical expert appraisal is produced with a view of identification of objects by their
images photos, photographic materials and laboratory accessories on traces on negatives
and positives, ascertainment of type and mark of "unknown" photofilms, detections on
photos traces of tampering , ascertainment of other circumstances linked to photographing
and handling of photographic materials (photos, photographic paper).
Thus, phototechnical expert appraisal tasks are subdivided on:
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Identification - associated with identification of specific object (a picture, a negative, a
film);
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Classification - associated with specific object (a photo) belonging to certain group
according to existing classification;
-
Diagnostic - associated with determination of object properties (a picture, the facsimile),
a method of detection its manufacturer, original form recovery.
1.2.1 Practical tasks of identification
The immediate practical task of identification of records can be put in various variants. In
practice of ascertainment and protection of copyrights, and also detections of a source of
media object the most often situations are when record on the initial carrier is exposed to
identification - ascertainment or a refutation of the fact of an origin of record from the
presented device is required, or the record copied on other carrier (possibly with automatic
format conversion, compression of dynamic range or other variants of postprocessing) is
exposed to identification. In the latter case initial record obtaining, as a rule is complicated,
and frequently impossible. It is required to determine a record ownership to the device
presented by means of another records set certainly acquired with it.
1.2.2 Digital watermarking as a technique for digital media data identification
The most known decision for maintenance of such protection, in particular the rights to the
media information presented in a digital form, is application of digital watermarks (DW).
Robust DW represent some information which is built in readout of a signal marked by
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