Panasonic sensor tackles key photo problem--dynamic range

This image, from a Panasonic paper at the ISSCC computer-chip show, shows a sensor with a better ability to span bright and dark areas in a photo. It works by combining three shots into a single high-dynamic range image using a new Panasonic image sensor.

(Credit: Panasonic)

SAN FRANCISCO-- Panasonic showed technology on Monday that could shift the digital photography trend of high-dynamic range photos off the computer and directly into a camera image sensor.

And it works through a variation of a familiar photographic technique called exposure bracketing. For years, photographers challenged by tough lighting conditions have taken multiple pictures of the same scene at different brightness levels--bracketing--to help ensure one photo has a good balance shadow and highlight details.

More recently, with the advent of computers, these bracketed exposures can be combined into a single high-dynamic range (HDR) image that captures both bright and dark areas--for example both the subtle tones of both a bride's white wedding dress and a groom's tuxedo--that lie beyond the abilities of the camera taking a single shot.

In research shown here at the International Solid-State Circuits Conference, Tokayoshi Yamada of Matsushita Electric Industrial--better known as Panasonic to most people--showed technology that he said lets an image sensor capture that high-dynamic range information.

With today's sensors, "You can get either highlight or shadow detail, depending on the exposure time. To get much wider dynamic range images, we need to combine these different-exposure images," Yamada said.

Yamada showed a 177x144 pixel image sensor that takes three photos of the same scene in rapid succession. In one example, he said, the first exposure lasts 1.5 microseconds, the second 150 microseconds, and the third 15,000 microseconds (not far from a 1/60 second exposure). Extra circuitry built into the sensor records the data from the multiple exposures and uses an assortment of electronic capacitors to combine it into a single image that spans a greater dynamic range.

The image can span a dynamic range of 140 decibels compared with ordinary sensors with a 60dB range when working at a frame rate of 15 frames per second, the researchers said.

In his presentation, Yamada showed a resulting image taken of a regular incandescent light bulb. With conventional sensor technology, a few of the words printed on the bulb were visible, but most were washed out in a blown-out white patch near the bulb's filament. In the Panasonic sensor's image, not only were most of the words visible, but also the helical coil of the filament was.

Combining multiple exposures has been possible before, but only using technology that recorded the multiple exposures in separate areas called frame memories, Yamada and his Panasonic colleagues said in a paper on the subject.

Despite efforts such as Fujifilm's SuperCCD sensors, camera buffs are often frustrated by the image sensor dynamic range of that's significantly weaker than what the human eye can detect. Although the Panasonic research shows some promise, though, photo nerds should rein in their hopes: the research showed only a black-and-white images so far and is suited "for automotive and security cameras," according to the researchers' paper.

[ElMartino1]

It was just a matter of time before someone did this

I don't see 'much' use for this in photography, but as the article says, this is about security cameras and specialized applications.

Otherwise, isn't it simply a built in HDR tone-mapper? Software on a larger digital camera could do this same thing without the need of any special sensor, just so long as people actually rtfm and expect the three mirror slaps for DSLRs.

[djacobow1]

no need for three mirror slaps

One will do, but the shutter will have to open three times (electronically or for real).

I think this would be a cool DSLR feature, but depending on how quickly the camera could get the multiple images taken, a tripod would be absolutely required (as well as a static subject).

I personally think HDR images look a little odd, but that's me.

[ArtInvent]

Pentax's new slr does something similar

Clearly to me at least, dynamic range is the next big problem that digital camera makers need to tackle, now that we don't need more megapixels.

The Pentax K20d can take three actual exposures in succession and combine them in-camera. This is pretty cool, though it can really only be used for still subjects and tripod use.

[fred dunn]

When are they going to put it in their cameras?

I like Panasonic's Lumix line with their Leica lenses. This would just be icing on the cake.

[hbwilliams]

Not new technology at all!

Real-time on-camera wide dynamic range processing at 30 frames/sec has been offered on video security cameras for _several_ years from many manufacturers, where DSP processing boosts dark areas and/or dodges bright areas, essentially varying the exposure of different parts of each frame to improve image captures in contrasty or imbalanced lighting. I've often wondered why it wasn't adapted or didn't evolve from still cameras. Sort of strange to me that this press release makes it look like some sort of a new development.