January 26, 2007 7:45 AM PST
Vista to give HD Photo format more exposure
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"We know we don't live in a world where things don't travel outside our ecosystem. We wanted to make sure anybody who wants to consume or create HD Photo has the ability to do that without any real encumbrance," Weisberg said.
Microsoft has won some support outside the software realm, too. "There are several manufacturers that have begun shipping or who are close to shipping HD Photo-enabled silicon (chips), but that will take time," Weisberg said, a step that's necessary for built-in camera support.
But the format is still a Microsoft standard, not an industry standard governed by a neutral consortium to represent others' interests. That can be a problem--for example, Apple has said it would like Adobe's DNG better if it were an industry standard.
Weisberg, though loquacious on many HD Photo subjects, is conspicuously quiet on the matter of standardization, saying only, "It's something we're always looking at."
HD Photo sales pitch
How exactly is HD Photo better than JPEG? Malvar and Weisberg have a multitude of arguments:
For each pixel, HD Photo stores at least 16 bits of data for each color, compared with 8 bits with JPEG. That means subtle tonal variations in shadowy or bright areas can be preserved, even through the editing and printing process. And for the cutting-edge crowd, it can store 32 bits per color, useful for combining multiple photos into a "high dynamic range" image that spans the darkest darks to the brightest brights.
HD Photo's compression algorithm produces images that have twice the quality as JPEG at the same file size or the same quality at half the file size. The algorithm uses simple instructions that can be relatively easily built into cameras' image-processing chips.
HD Photo builds in smaller "thumbnail" images for quick viewing of files at small sizes. In contrast, a computer operating system must generate JPEG thumbnails.
The encoding algorithm, set to its highest standard, is "lossless," meaning that it preserves all the image data with no loss of quality. JPEG is "lossy." And although JPEG 2000 has a lossless feature, it requires a separate algorithm and therefore, in the case of camera chips, more circuitry.
HD Photo uses Microsoft's scRGB color space, which spans a much wider gamut of possible colors than the universally supported but widely derided sRGB scheme. "HD Photo adds support for a higher range of colors, which is becoming more important," Connor said.
And although cameras and computers typically describe colors in RGB terms--varying amounts of red, green and blue--HD Photo also can use CMYK that uses cyan, magenta, yellow and black. That's useful for sending images to printers, which often use CMYK inks.
The algorithm can decode only a selected portion of the HD Photo image that needs to be displayed, rather than the entire image, which reduces memory requirements and speeds up performance. It can also be encoded chunk by chunk without having to store the entire image in memory.
HD Photos can be easily rotated in 90-degree increments. JPEG images must be decoded and re-encoded, degrading quality slightly with each change.
HD Photo images can be gargantuan--262 million pixels on an edge, or 68.6 terapixels total, as long as the compressed image doesn't exceed 32GB in size.
Microsoft knows it will need a strong pitch to spread HD Photo beyond Windows and into the entire digital photo world.
"The camera manufacturers will think, 'If I produce an image, will the neighborhood drugstore print it? Otherwise I'll keep JPEG,'" Malvar said. "We would like such a transition to happen, but we are realistic that it may take some time until the whole ecosystem is in place."
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