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Longhorn Raw Image Support

Early this month, Microsoft revealed that it would natively support Raw image files in Longhorn, its next generation Windows operating system and, to a lesser extent, in Windows XP as well, through a free Power Toy add-on. Most Windows users are probably unfamiliar with Raw images, however, so I spoke recently with Josh Weisberg, Group Product Manager for Windows Digital Media at Microsoft about this development and how it will make Longhorn more attractive to digital camera users.

Raw image files are often described as digital negatives, because they are uncompressed, unprocessed files that accurately portray the data captured by the sensor in a high-end digital camera. Most consumer-grade digital cameras do not currently offer Raw image support. Instead, they typically offer various types of JPEG images, which are compressed using a lossy compression algorithm. This means that JPEG images drop image data in order to maintain small file sizes.

That's fine, of course, but the problem with JPEG files is that they are recompressed, losing further data, every single time they are edited and saved back to disk. Thus, if you take a JPEG image file and edit it several times in a row, you could actually permanently damage the quality of the image. That's scary, mostly because so few of the millions of people who are now digital taking pictures are even aware of this problem.

"If you open a JPEG file in an editing application, make some changes, and then save it, the file is recompressed," Weisberg said. "Do this two to three times, and you'll introduce lots of artifacts to the image file. The data in a JPEG file changes every single time you save it, even if you don't change anything. There's no middle ground."

Professional grade cameras typically support Raw image formats in addition to JPEG. The problem is that each camera maker--and in most cases, each camera model--supports a completely different Raw image format. That is, there is no such thing as a "standard" Raw image file format. Instead, there are hundreds of incompatible formats.

"Raw images contain a data mosaic like voltages," Weisberg told me. "They're not actually comprised of pixels. So you can't view them without decoding them first." Until recently, the only way to view or edit Raw images was to use specialized software that camera makers shipped with their cameras--such software is generally lousy to pretty good at best--or to use a high-end photo editing application like Adobe PhotoShop.

Adobe tackles Raw images

As I explain in my Connected Home Media article, Working with Raw Image Files, however, Adobe's support of Raw image files is tenuous at best. The problem is that there are so many formats and that, until this year, some camera makers weren't particularly interested in revealing the details of their proprietary formats. In particular, the company was never able to reach an agreement with Canon or Nikon. So Adobe began reverse engineering the most popular Raw image formats so that its PhotoShop tool could help professional photographers edit their images.

Adobe's efforts are understandable, but the reverse engineering approach is doomed to failure. That's because the company often can't support new high-end cameras until months after they're released, stranding high-end users who wish to use PhotoShop with their new camera. These users wait for Adobe to ship plug-ins for new cameras that enable the support they need. And the company is on a never-ending treadmill, forced to manually support every new format that comes down the pike. There's also a legal issue. What if Adobe is sued for its efforts? Camera makers consider their Raw image formats to be valuable intellectual property, technology that differentiates their cameras from the competition. It's unlikely, but one of these companies could conceivably pursue Adobe for reverse engineering their formats.

Adobe realizes the problems with this approach of course, and in late 2004, it offered a new Raw image format called Adobe DNG (for Digital Negative) and a converter tool that now converts 75 types of Raw image formats into DNG. In a bid to end the complication of multiple Raw image formats, the company also offered DNG to camera makers for free, hoping that some would offer it in their high end cameras as an optional image format. Given the company's success making PDF a de facto standard, Adobe may be on to something. So far, however, DNG support has been lukewarm.

What's been missing, of course, is low-level support for Raw image formats in a mainstream operating system. Windows XP, for example, allows you to view, manage, and edit bitmap (BMP), JPEG, GIF, and other image formats natively in the Explorer shell. And if you view a folder full of image files in XP, you can optionally display them using the Thumbnail icon view, which provides you with a nicely rendered view in which each icon is a miniature representation of the underlying image. Raw images, meanwhile, appear in XP with an ugly default icon, and if you try to open one, the system won't know what to do with it.

Apple's Raw image support not what it seems

Curiously, Apple was the first operating system vendor to announce support for Raw images in its products. In his January 2005 keynote address at MacWorld San Francisco, Apple CEO Steve Jobs announced that iPhoto 5, part of the iLife 05 suite of digital media applications, would support Raw image files. Also, the company revealed that the Preview application in Tiger (see my review), the latest version of Mac OS X, would support Raw image files.

That's all well and good, but Apple's support of Raw image formats is more PR-speak than anything else. First, Apple, like Adobe, is simply manually reverse engineering each Raw image format that they support (except for Adobe's DNG format, which is publicly available), so they've joined the same treadmill that Adobe found itself locked into. But Apple supports a much smaller range of Raw image formats than does Adobe, so chances are pretty high that your camera won't be supported anyway. Since Tiger debuted in April, Apple hasn't updated the list of Raw image formats it supports.

"Tiger does work with the Adobe DNG format," Weisberg admitted. "But can you see Raw image thumbnails in the Finder? Can you search for them in Spotlight? Can you double click on those files and open them in an appropriate application?"

And iPhoto, of course, is not the professional tool that Raw format users expect. Further problematic, when you import Raw files into iPhoto, the application immediately makes JPEG copies and then applies any edits to the copies, and not the original. This results in the JPEG quality loss problem described above, which is bad. But the user is unaware that edits aren't being done off the original uncompressed file, which is perhaps worse. At least when you import Raw image files into PhotoShop, you are given editing options right up front, and those edits are applied before the resulting file is compressed.

There are other issues. Many Raw images look horrible in iPhoto: When you open a Nikon raw image file in iPhoto, for example, you will not get the same quality as with PhotoShop or Nikon's proprietary software. "Apple has gone the same route as Adobe but not done as good a job," Weisberg said. "Their solution commits them to a lifetime of building it themselves and doesn't provide any true platform support. Also, they're cracking someone else's intellectual property. And it's not open or extensible, and doesn't offer [application programming interfaces] (APIs) that are broad and open for others to use."

Enter Longhorn

"We decided we needed to solve this problem in Longhorn," Weisberg told me. "So we sat down with Adobe and told them we'd like to solve it in the operating system. We asked them what they learned working with Raw image formats, and what they recommended that we do. We also sat down with Canon, Nikon, and other camera makers and worked out a proposal that everyone could live with. We iterated it with them, and they all helped design and build it."

What they arrived at was an agreement that represents a huge step for both Microsoft and its users. In other words, Microsoft didn't go their own way on this one. Instead, they worked with relevant industry leaders and interested parties to ensure that the resulting solution was appropriate for everyone.

There are two parts to this initiative. First, the Windows Imaging Codecs in Longhorn, which are used for image formats such as JPEG, GIF, and PNG, will be extended to support Raw image formats as well. Camera makers that support the initiative--Canon and Nikon, currently, though others are expected to jump on board soon--will write codecs for their formats that plug directly into the Longhorn imaging architecture. Thus, Longhorn will be able to natively decode Raw image files in the same way that it supports JPEGs.

"These Raw image files will be first class citizens in the Windows shell," Weisberg told me. "They will behave just like JPEG files, so you can organize them in the shell, display thumbnails, edit them, print them, and share them. They will provide meta data information for various purposes, and will have relevant contextual menus when right-clicked." Understand how far reaching this is. Once Raw images are supported natively by Windows, they are, by extension, compatible with Windows applications too. You'll be able to drag and drop a Raw image file into an application like PowerPoint, or copy the contents of a Raw image file the Clipboard and then paste it as needed.

Microsoft will also provide the eight most common Raw image conversion filters (exposure correction, white balance, and so on) in the operating system's Picture and Fax Viewer application. This means that the basic image viewer application in Windows will natively support some of the same editing features that you need to purchase Adobe PhotoShop for today.

The second part of this initiative is a new set of APIs that will allow developers to create third party applications that support these conversion filters. This will allow non-professional applications to perform PhotoShop-like editing functions for the first time, without the need for them to individually create code to perform these conversions. "This means you don't have to commit to supporting all these different formats," Weisberg explained. "Instead, you just have to support a single codec."

Microsoft is starting a certification program for camera makers to ensure that they conform to the standard. And of course, Longhorn will only work with codecs that are digitally signed by Microsoft for security reasons. The program is open to one and all, and not just the Canons and Nikons of the world. "Any camera maker, or anyone who wants to make a Raw image format of their own--it doesn't even have to be the original manufacturer--can do so," Weisberg told me. "We have an arbitration process to pick the best one if there are multiple choices [for an individual Raw image format]."

Aside from the obvious, Longhorn's support of Raw images is important because, for the first time, a common Raw image format is being supported by camera makers and, conspicuously, by Adobe, a company many might have expected to resist Microsoft's efforts. "Canon and Nikon are the big ones," Weisberg noted. "Most people using Raw formats are using their equipment."

However, that doesn't mean Microsoft is ignoring other camera makers or that other camera makers have refused to join Microsoft's initiative. Sony and Kodak are reportedly in talks with the company, and others will no doubt come on board over time.


In Longhorn, the end user wins because most Raw image formats will be natively supported right in the operating system, regardless of their skill levels. Pro users, of course, will continue to migrate to more complete solutions such as PhotoShop, so Adobe isn't left in the cold. And camera makers can continue innovating with new Raw image formats but be assured that by providing a Longhorn codec that those formats will be more broadly available to third party software products.

If you're interested in getting a taste of this image type support, Microsoft has shipped its RAW Image Thumbnailer and Viewer for Windows XP. This free tool lets you manage Raw image files in the XP shell, using built-in thumbnails, and view and print them from a Picture and Fax Viewer-like applet. What you can't do with this tool, of course, is edit Raw image files. For that, you'll need Adobe PhotoShop CS/CS2/Elements 3.0 or Microsoft Digital Image Suite 2006, the latter of which I'll be reviewing here soon.

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