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Could JPEG XR deliver cheaper, better burst shooting?

The required scads of buffer memory fast image-processing hardware holds back the widespread support of raw-format files for continuous shooting in low-cost cameras. JPEG XR could present an acceptable alternative.

Lori Grunin

When Canon's Chuck Westfall popped by last month to give us a sneak preview of the EOS Rebel XSi, I expressed my disappointment that the camera's raw continuous-shooting maxed out at a mere 6 frames. I asked Chuck if there was anything on the horizon that might deliver a better raw burst-shooting experience for the can't-afford-a-Mark-III set. His immediate and somewhat unexpected response: "JPEG XR." A few weeks later, I put a similar question to Casio's Scott Nelson, a product manager in the camera division, as he showed off the company's burst-mode blitzkrieg, EX-F1--a camera which doesn't support raw for burst shooting. He, too, indicated that JPEG XR held the key for delivering higher-quality, high frame-rate photos at reasonable prices.

Never let it be said that I couldn't recognize a trend once it whacked me on the head a couple of times.

Raw files--data straight from the sensor--place a heavy performance burden on a digital camera. Though they're same dimensions as JPEGs, raw files support 12-bit or deeper color, while JPEG and its widely ignored successor, JPEG 2000, support only 8 bits. That makes the raw file footprint bigger, even when compressed, and increases the required amount of buffer memory. Furthermore, while JPEG-processing chips are cheap, the proprietary nature of raw files makes it necessary to use dedicated silicon for processing them with any speed. That's a lot of cost to add to a sub-$1,000 dSLR or enthusiast shooter.

Microsoft's JPEG XR--the XR stands for "extended range"--provides some of the image-quality benefits of raw while offering the smaller file size and non-proprietary processing benefits of JPEG. Keep in mind that JPEG XR doesn't replace raw. It simply offers better compression algorithms, and a wider dynamic range than JPEG. At best, one might find a JPEG XR photo visually indistinguishable from a processed raw file. That lets it stand up to retouching better--suffer from less degradation--than its predecessor. For shooters in that market segment, that may be enough.

Clearly, no one's talking about actual products yet, and JPEG XR-as-standard hasn't even attained Committee Draft status within the ISO's JPEG committee (that's scheduled for the end of March). But the fact that I'm actually hearing about it in conversation makes me think that we might start to see some implementations by next year. While I still would prefer longer raw bursts, JPEG XR strikes me as a reasonable compromise.