MPEG Photo Player Application Format
MPEG doc#: N7325
Date: July 2005
The Digital Camera is one of the most popular consumer digital devices, with estimates showing over 100 million units sold worldwide in 2001 and 257 million camera phones shipped worldwide in 2004. In the next two years the sales of digital cameras are expected to overtake sales of their analogue counterparts in Japan, US and Europe.
Consumers appreciate the ease with which digital photographs can be taken, copied, processed and shared. However, only a few months’ use of a digital camera will typically generate a library with thousands of digital photographs. Performing many common tasks, such as searching for photographs of interest, becomes a tedious and time-consuming exercise. As a consequence, there is a growing demand for the provision of suitable metadata, such as information about the photo content (e.g. the subject being photographed), author, shoot location, imaging parameters, etc. Such metadata needs to be stored in a standardized format, so that it can be easily interchanged between various digital devices.
The need to store metadata generated early in the acquisition process has been reflected in the Exif (Exchangeable Image File) standard, which is commonly adopted by the camera manufacturers. However, while very useful, the Exif standard is limited in scope to basic “acquisition” related information.
MPEG has developed the MPEG-7 standard, defining rich metadata descriptions for still images, video and audio. Together with the MPEG-4 file format this represents an ideal environment to enable the “Photo Player” user experience, and, moreover, to extend that experience in new directions. The Photo Player MAF specifies a standardised solution for carriage of the image data and associated metadata to significantly improve the user experience.
In one example of this, a simple but very efficient collection structure can be introduced by grouping images by the occasion or situation in which they were taken. Examples of situations include a family dinner, a trip to a beach, etc. Such a structure is very natural for the users since they will often remember the circumstances much better than the event date or filename. It provides a simple, intuitive and effective means to browse through the collection and, moreover, can all be done automatically based on the visual descriptors and the time information.
Another possibility is to automate the labeling of the images themselves. Manually labeling a large collection is a very tedious task and is seldom performed by users. However, even quite generic and simple labels often prove very helpful when searching or browsing through large image collections. Simple labels such as indoors/outdoors, landscape, architecture, waterfront, sunset, etc, can be automatically assigned to images based on MPEG-7 Visual descriptors.
For these and other multimedia applications, it is important that the metadata is as portable and interoperable as the images. Just as the content itself is created and consumed on diverse devices, so the metadata must be. This is the key to what is offered by the Photo Player application format – it enables a broad array of desirable content-management functions across platforms, by standardising the format for exchanging the necessary information.