Automatic indexing of video documents
Establishment of a shot hierarchy
The splitting of a video document into shots corresponds to the basis
of a bigger hierarchy, which aims at grouping several shots together
according to chosen criteria, in order to reach a higher semantical
level for the understanding of the document.
Therefore, any video
document can be structured and splitted into shots, which themselves
constitute scenes (same unity of place for example, but different view
points) and sequences (same unity of subject), etc. when grouped
Let us take the example of a TV newscast which is of great interest in
our framework. For the indexing process, one has to be able to group
the different shots to extract each news report as a entire unity,
and, from a given report (that is to say a sequence with the above
terminology), to extract all scenes and illustrations of this report.
When applied to the key frames of two different shots, the algorithm of transition detection allows one to
establish relations between the different shots. The only change to
apply to the algorithm consists in the choice of a little higher
It is besides interesting, still in an indexing framework, to be able
to say, if during a shot, the scene was modified or not. A motion
estimation should of course provide a lot of useful information in
this case. But once again, the use of the detection algorithm applied
on key frames of a same shot, is a simple way to get a quick idea of
the answer to the question "Was there any change during this shot ?"
This time the chosen threshold value is between the global threshold
and the relation threshold.
These two additional informations, related shots and inner shot
change, are illustrated for an interview sequence. The key frames of
the sequence are first proposed in Fig.1 ; Fig.2 and Fig.3 present
respectively the results of the inner shot change detection and the
results of the extraction of related shots.
|Fig.1 Key frames of the sequence interview - CopyrightA2/CMM/ENSMP. Back to top|
| Fig.2 Results of the inner shot change detection, sequence
interview. Back to top |
|shot 0 -
|shot 2 - shot 4|
|Fig.3 Results of the detection
of related shots, sequence interview. Back to
The detected change in the first shot corresponds to the
text disappearing in the first frame.
Some additional results of
relation and change detection are also proposed here.
All the original images in this page come from TV newscasts of the
french TV channels TF1, FR3, A2 or M6 and are therefore copyrighted by
these channels. All other images or photos are copyrighted by the
CMM. These documents are protected by the law on the author rights,
each non-authorized copy or use is therefore strickly forbidden.
Last update : 01 - 06 - 99