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HD Photo, Version 1.0 (Windows Media Photo)

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Table of Contents
• Identification and description
• Local use
• Sustainability factors
• Quality and functionality factors
• File type signifiers
• Notes
• Format specifications
• Useful references
Format Description Properties
• ID: fdd000243
• Short name: WMP_1_0
• Content categories: still image
• Format category: bitstream encoding, file format
• Last significant update: 2007-01-29
• Draft status: Full

Identification and description Explanation of format description terms

Full nameHD Photo, Version 1.0 (formerly Windows Media Photo)
Description Format for continuous-tone still images that supports a wide range of features including:
• Multiple color formats for display or print
• Fixed or floating point, high-dynamic-range image encoding
• Lossless or high-quality lossy compression
• Efficient decoding for multiple resolutions and sub-regions
• Minimal overhead for format conversion or transformations during decoding
The developer states that the format delivers "a lightweight, high-performance algorithm with a small memory footprint that enables practical, in-device encoding and decoding."

Support for HD Photo is provided by the Windows Imaging Component (WIC) installable codec architecture and the Windows Presentation Foundation (WPF; concerned in part with user interfaces) developed for the Windows Vista operating system. Microsoft states that Vista represents the integration of imaging at the operating system level, reducing the level of activity required of specific applications.
  Production phase   Used for content in middle and final states.
Relationship to other formats 

Local use Explanation of format description terms

LC experience or existing holdingsNone.
LC preference None.

Sustainability factors Explanation of format description terms

Disclosure Developed by the Microsoft Corporation.
  DocumentationThe container format and API are specified in the HD Photo Feature Specification (2006); in February 2007, available from http://www.microsoft.com/whdc/xps/wmphoto.mspx. Information about the HD Photo compressed bitstream format and how to implement an encoder and decoder are part of the HD Photo Device Porting Kit 1.0 (DPK) provides; in February 2007, available from http://www.microsoft.com/whdc/xps/hdphotodpk.mspx.
Adoption Introduced in 2006, with some dependency on the level of adoption of the new Windows Vista operating/application system, available in 2007. Thus no significant adoption of WMP_1_0 in 2006-07.
  Licensing and patent claims Licensing applies to applications that create or display images, not to the images themselves. A Microsoft Web page consulted in August 2006 and no longer available in January 2007 (http://www.microsoft.com/windows/windowsmedia/licensing/wmphoto.aspx) stated, "Under most conditions, Windows Media Photo technology is available free of charge; royalties are associated only with specific licensing conditions."
Transparency Depends upon algorithms and tools to read; will require sophistication to build tools.
Self-documentation WMP_1_0 uses a "TIFF-like" file container to store image data in a table of Image File Directory (IFD) tags, using tag numbers from TIFF's baseline, extended, and "private" sets. Examples of tags drawn from extended and private TIFF sets: ICCProfile (34675), XMPMetadata (700), and EXIFMetadata (34665). For an overview of tags, including a listing of WMP_1_0 tags, see Tags for TIFF and Related Specifications.

The large number of possible image encodings are identified by means of GUIDs specified by Microsoft. (This contrasts with an approach based upon the placement of data in a set of tags for such features as bits per pixel, photometric interpretation, and so on.)
External dependenciesNone
Technical protection considerationsNo DRM technology; see Notes below.

Quality and functionality factors Explanation of format description terms

Normal renderingSupported.
Clarity (support for high image resolution)Very high levels of image quality are supported. The Wikipedia article "HD Photo" (as of January 29, 2007) reports, "WMPhoto supports various color formats and multiple fixed and floating point numerical representation, thus giving a wide range of compression options. . . . While digital photography needs are satisfied by the Basic format, 3D rendering or advanced image processing scenarios require the Advanced format. Microsoft claims that Windows Media Photo offers a 'perceptible image quality comparable to JPEG 2000 with computational and memory performance more closely comparable to JPEG and delivers a lossy compressed image of better perceptive quality than JPEG at less than half the file size, and that the lossless compression compresses images 2.5 times.'"
Color maintenance Excellent support; files can include ICC profiles; extended color gamuts are supported.
Support for graphic effects and typographyNot investigated
Functionality beyond normal image renderingNot investigated

File type signifiers Explanation of format description terms

Tag typeValueNote
Filename Extensionwdp, hdpFrom the Wikipedia article "HD Photo" (as of January 29, 2007)
Magic numbersHex: 49 49 BC
ASCII: II.		From the The File Extension Source
Internet Media Typeimage/vnd.ms-photoFrom the Wikipedia article "HD Photo" (as of January 29, 2007)

Notes Explanation of format description terms

GeneralRegarding compression: The Wikipedia article "HD Photo" offers a good overview of the format (consulted on January 29, 2007). The section devoted to the compression algorithm reports, "Windows Media Photo uses a reversible color space conversion, a reversible lapped biorthogonal transform and a non-arithmetic entropy encoding scheme, which is very efficient in preserving high frequency image data. This makes the algorithm retain a higher image quality at high compression ratios. The transform operation needs 3 multiply and add operations and 7 add or shift operations at the highest quality level and in the highest performance mode, 1 multiply and add operation and 4 add or shifts are required per pixel, giving the codec a high performance. Windows Media Photo processes images in 16x16 macroblocks."

Regarding digital rights management: In a blog, consulted in August 2006, HD Photo Program Manager Bill Crow commented:
  • Windows Media DRM is ideal for publishing audio and video, but is really not that useful for still photography. Most commercial scenarios for digital photos require that the customer receive direct access to the image, which basically defeats the approach used by Windows Media DRM (where the goal is to protect the content all the way to the glass or speakers). Also, Windows Media DRM is designed for a "few to many" publishing model; the DRM license gerneration technology does not easily allow anyone to generate their own DRM licenses.
  • While we are looking at DRM for photos for possible support in the future, the initial implementation was deliberately been designed to be simple, lightweight and easy for partners to implement directly in devices. That said, you can currently use Windows Document Rights Management for very effective management of rights access to digital photos.
  • We're investigating more comprehensive solutions to manage digital photo access rights, copyright protection and provenance guarantees as features for future versions of Windows Media Photo.
Other notes: Bill Crow's own blog is informative; here are some excerpts collected in August 2006:
  • Our current encoder tools include a choice between the sample applications that are part of the Windows Media Photo Device Porting Kit (DPK) or an encoder utility based on the Windows Imaging Components (WIC) interfaces that we developed internally for our own testing purposes. Both tools are command line utilities, and each has its own specific strengths.
  • The fundamental goal with a high dynamic range, wide gamut pixel format is to never discard image information that falls outside the visible range. The entire tonal spectrum is always retained, regardless of the current exposure or color adjustments. Using fixed point or floating point values, pixel information is encoded using an extended numerical range. The visible portion of the numerical range is a subset of the total numerical range that can be encoded with fixed point or floating point values. . . . If color or exposure adjustment pushes a pixel value outside the visible range, rather than losing this value (as is the case with unsigned integer representations), the numerical value is still retained. If a subsequent adjustment brings that pixel value back into the visible range, the correct numerical value is fully recovered. This dramatically eliminates the issues and concerns with "flattening" a file. Most color or exposure adjustments are completely reversible, eliminating the need to restart with the original RAW file or an intermediate layered editing file.
History 

Format specifications Explanation of format description terms

URLs
• HD Photo Feature Specification (http://www.microsoft.com/whdc/xps/wmphoto.mspx)
• HD Photo Device Porting Kit 1.0 (DPK) (http://www.microsoft.com/whdc/xps/hdphotodpk.mspx)

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Useful references

URLs
• Wikipedia article (http://en.wikipedia.org/wiki/HD_Photo)
• Bill Crow blog; Crow is the Windows Media Photo Program Manager (http://blogs.msdn.com/billcrow/)
• Andy Simonds blog; includes exchange about DRM and other info (http://blogs.msdn.com/andy_simonds/archive/2005/10/06/477954.aspx)
• The File Extension Source (http://filext.com/)

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Last updated Thursday, 01-Feb-2007 18:15:40 EST

 
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