What is Multimedia Information Retrieval?
The multimedia information query by example (Multimedia Information Retrieval, MIR) is a search system to retrieve similar information (videos, images, sounds, etc.) based on its content. In the case of images (Content-Based Image Retrieval, CBIR), the features are treated according to their context in relation with colors, shapes, textures or any other information that may result from the image itself.
Most of the techniques used in CBIR from the viewpoint of image processing are based on the field of Pattern Recognition and Image Analysis, where the main objective is the classification of objects in a number of categories or classes. If we work with videos (Content-Based Video Retrieval, CBVR), the techniques can be very similar, incorporating in addition features such as movement, relations between frames, quick changes between scenes, etc.. (digital video processing).
This does not conflict at all with the classic treatment of this information in databases by metadata (tags) or additional textual information can be entered automatically (eg, date of collection, device characteristics, making parameters , etc.) or manually (author, descriptive labels in the document, etc.).
Information should be indexed to reach an efficent (fast) and effective retrieval. Therefore metadata are meaningless for large image collections and the automatic indexing and retrieval are considered based on what is in the multimedia information according to its content or features (primitive or processed properties).
In these types of searches the subjectivity of human perception greatly affects the outcome of the queries. Thus, the automatic feature extraction through computational methods must take into account this human factor. It is sometimes quite difficult to obtain similar results computationally and the user really wants. This discrepancy is what is called semantic gap. The computational characteristics is not that high semantic content that have the human perceptual characteristics. Hence this is the reason for MIR systems.