Hitachi has developed MPEG-7-compliant, image-searching technology for instant searches of a scene from a large volume of digital images. This technology significantly reduces the features of the images to be added to images for retrieval, so as to cut by half the cost of storing the features, as well as search time.
The technology has the following features:
(1) Low-cost description of the features of the retrieved images, whereby frame images with the same contiguous features are grouped and the features are then described for each group of frame images. This method allows the cost of storing the features to be cut by half by reducing the amount of descriptions of the features to 20 percent on average, in comparison with the conventional method of describing the features by each frame while taking it. For example, this enables a single CD-ROM to store an amount of descriptions of features corresponding to one year's worth images.
(2) High-speed comparison of scenes in images, whereby an algorithm is used for directly comparing the features of each frame image with those of another within an identical group formed through the above means (1), as a method of cross-checking video scenes when retrieving images. This method enables trimming the time needed for searching images by 50 percent on average versus the previous method.
As this technology enables implementation of the related software to an embedded CPU, that is a digital signal processor running between 10MHz and 100MHz, the feature can be loaded on a low-cost video or imaging terminal. If the CPU in a video or imaging terminal runs at around 450MHz, a specific scene can be searched from 24-hours' worth TV image data within a second.
It can be also applied to a wide range of systems for retrieving massive digital pictures, for example, from a large-scale digital archive system in TV stations or universities to a consumer home video server, because the technology can significantly reduce the cost to store data needed for retrieval, while keeping the degree of accuracy of searching, as well as the time for searching images.
Hitachi plans to apply the technology to the "Mediahall," Hitachi's management and distribution system of MPEG-4 images, and then deploy it to image distribution systems for mobile and high-speed Internet communications, image archive systems and imaging support systems.
The MPEG-1, MPEG-2 and MPEG-4 systems are all for standardizing the compression scheme of animation and voice data. The MPEG-7 system is to standardize a set of description schemes targeting data to be used for cross-checking when retrieving voices, images and pictures