Supporting MetaData in Image Files through GDI+
Supporting MetaData in Image Files through GDI+
From http://www.microsoft.com/hwdev/display/GDIplus_Metadata.htm 2001-04-23.
Microsoft is encouraging industry groups and vendors who define image file formats to specify and support a baseline set of metadata to help promote widespread use of specific metadata by the industry and consumers. This download article discusses how Microsoft is supporting metadata with GDI+ and recommends enhancements for metadata support in the industry.
Download Supporting MetaData in Image Files through GDI+
(24 KB zip file in Microsoft Word format; Version 1.1; file date: April 12, 2000)
Integration of relevant metadata in images provides an opportunity for participating industries to take imaging to the next level. Image metadata is essentially non-picture information that is bundled with picture information in a file. Metadata can include information such as the date and time the picture was taken, whether a flash was used, which camera model was used, and even audio annotations. Metadata is a key supporting technology for content management. The content management services built in to the Microsoft Windows Millennium Edition (Windows Me) and later Windows operating systems uses metadata extensively. Metadata provides benefits to users, application developers, and hardware vendors:
Metadata helps users organize digital images. As digital cameras and scanners become more widely available, users are faced with managing hundreds or thousands of images.
Using the content management capabilities of the Windows operating systems, users can sort and search their images on metadata items such as date and time, camera make and model, or location, for example.
Metadata helps devices render digital images with higher quality. Currently, devices render images as best they can, based on average settings for the average image. Improving the quality of a given rendering requires the user to make manual adjustments.
Vendors can use metadata such as brightness and exposure bias to refine device algorithms for rendering images to produce higher-quality images automatically, with less need for user intervention.
Metadata helps vendors manage image files in workflows. Currently, it is difficult to obtain simple information such as when and where a picture was taken with a digital camera or what camera model was used so that the printer vendor can compensate appropriately.
Vendors can use metadata to enhance image reproduction. For example, suppose a vendor produces both digital cameras and printers. Having metadata available to the printer driver allows the vendor to enhance the end-to-end quality of the image reproduction system.
Metadata enables users to better use their images. Users can also take advantage of metadata such as organizing pictures by the date they were taken or the digital camera used, or annotating pictures for sharing or storage. For example, a user might take pictures at a vacation resort, download them to a PC, and annotate them using an application based on GDI+ before sending the pictures to friends and relatives, who might further annotate the pictures before forwarding or storing them.
Microsoft is supporting metadata in image files through GDI+, the next-generation graphics engine for 2D vector graphics, imaging, and typography for Windows-based and Web-based applications. GDI+ supports a number of native still image file formats, including BMP, JPEG, TIFF, PNG, GIF, WMF, and EMF. In turn, GDI+ provides core services for managing files in these formats to Microsoft Windows platforms. Vendors can use GDI+ to read and modify metadata in image files. Vendors can also use GDI+ to implement image codecs for proprietary file formats that would enable any GDI+ application to seamlessly open files in those formats.
GDI+ makes more extensive use of metadata in image files than earlier versions of Windows operating systems, and more image metadata is exposed to users. Vendors who generate image files are encouraged to store valid and presentable information in all possible metadata items.
Application developers are also encouraged to use Windows Image Acquisition (WIA) to set device properties that generate metadata if the camera supports this behavior. For example, an application might recognize that the date and time of an image is missing and communicate with the device through WIA to set this value so that subsequent images will contain date and time metadata. Microsoft recommends that vendors of cameras and other devices that generate still images and image metadata take advantage of WIA to communicate with the PC, rather than simply representing their devices as disk drives. For information, see http://www.microsoft.com/hwdev/wia/
A GDI+ developer beta is currently planned for 3Q2000. For information, contact Microsoft at firstname.lastname@example.org.
This download article presents guidelines for standard support of metadata by the industry. It recommends a baseline set of metadata that future file formats should support, to promote interoperability. This paper suggests enhancements to facilitate organizing and searching files by metadata values, to take advantage of content management services provided by the operating system. It also discusses how GDI+ supports metadata in current file formats and provides reference information for the currently planned GDI+ APIs for managing metadata in image files.
[Cache version 2001-04-23]
Prepared by Robin Cover for The XML Cover Pages archive.