What's New for WIC in Windows 7
In Windows 7, Windows Imaging Component (WIC) has been updated with several new features. This topic provides a quick introduction to these new features.
This topic contains the following sections.
- Updates to the TIFF Codec
- Progressive Decoding
- Extended Metadata Support for JPEG, PNG, and GIF
- Multi Threaded Apartment Support
- Metadata Working Group Implementations
- Windows 7 features supported on Windows Vista and Windows Server 2008
- Related topics
The WIC TIFF codec has been updated for Windows 7 to support several features not supported by the previous version of WIC.
- Support for large TIFF files.
- Decode tiled TIFF images.
- Decode flat (planar) TIFF images.
- Decode JPEG encoded TIFF images.
Progressive decoding provides the ability to incrementally decode and render portions of an image before the entire image has finished downloading. This feature greatly improves the user experience when viewing images from the Internet, because the user does not have to wait for the entire image to download before decoding can begin. With progressive decoding, users are able to see an image preview with available data long before the entire image is downloaded. This feature is essential for any application used to view images from the Internet or from data sources with limited bandwidth.
For more information, see the Progressive Decoding Overview.
In Windows 7, WIC has extended its metadata support for JPEG, PNG, and GIF images.
- Added support for animated GIF and GIF properties.
- Expanded JPG metadata handlers to support chrominance, luminance, and comment metadata.
- Expanded PNG metadata handlers to support tIME, sRGB, iCCP, hIST, cHRM, iTXt, bKGD, and gAMA metadata.
- Added new 8BIM metadata handlers for ResolutionInfo metadata and IPTC digest metadata.
- Added new metadata handlers for Logical Screen Descriptor (LSD), Image Descriptor (IMD), Graphic Control Extensions (GCE), and Application Extensions (APE) metadata.
- Support for metadata that spans APPn blocks.
Objects within a multithreaded apartment (MTA) may be called concurrently by any number of threads within the MTA, allowing for better performance on multicore systems and certain server scenarios. In addition, WIC codecs that live within an MTA can call other objects that live within the MTA without the marshaling cost associated of calling between threads that live in different STA apartments. In Windows 7, all in-box WIC codecs have been updated to support MTA, including JPEG, TIFF, PNG, GIF, ICO, and BMP. It is highly recommended that codecs be written to support MTA. Codecs that do not support MTA will cause significant performance degredation in multithreaded applications due to marshaling. Enabling MTA support requires proper synchronization to be implemented in the codec. Exact implementation of these synchronization techniques is beyond the scope of this paper. A general reference for synchronizing Component Object Model (COM) objects is provided below.
There are currently a variety of metadata storage formats that contain overlapping properties, without any clear industry standard or guidance on consistent methods for reading and writing these metadata formats. To help with this variety of formats and properties, the Metadata Working Group (MWG) was formed. The aim of the MWG is to provide guidelines that ensure interoperability among a wide variety of platforms, applications, and devices. The guidelines established by the MWG apply to the XMP, Exif, and IPTC metadata fields, and to the JPEG, TIFF, and PSD image formats.
In Windows 7, the photo metadata handler and the metadata policy layer have been updated to read and write image metadata according to the guidelines established by the MWG. For more information on the Metadata Working Group (MWG) and the established metadata guidelines, visit the Metadata Working Group Web site.
The Platform Update for Windows Vista is a set of run-time libraries that enables developers to target applications to both Windows 7 and Windows Vista. The Platform Update for Windows Server 2008 is a set of run-time libraries that enables developers to target applications to both Windows Server 2008 R2 and Windows Server 2008. The Platform Update for Windows Vista and the Platform Update for Windows Server 2008 will be available to all Windows Vista and Windows Server 2008 customers through Windows Update. Third-party applications that require Platform Update for Windows Vista or Platform Update for Windows Server 2008 can have Windows Update detect whether the required updated is installed; if it is not, Windows Update will download and install it in the background. For more information about both updates, see Platform Update for Windows Vista
Build date: 11/29/2012