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Kodak fits 50MP into dynamic range

Jul 9, 2008 at 18:45 GMT

Kodak has announced the creation of a new medium format 50MP chip, to be used in the newly-unveiled Hasselblad H3DII-50. The KAF-50100 Image Sensor offers a sensitivity range of ISO 50 - 400 and the highest resolution currently available in the 36 x 48mm format. The company spoke to us to explain the chip and the technologies behind it.

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"We were being told two things by our customers," said Kodak: "The first was the need for more resolution, to give increased levels of detail. The cameras this chip will be used in can support this: they have headroom in terms of what their lenses can resolve. But, at the same time, we were being told: 'Don't take anything away that we already have,' particularly in terms of dynamic range."

Kodak says the new chip is the first of a new generation of sensors and is the first to utilize a new technology platform. There are three key technologies in the new chip to help improve responsiveness, color accuracy and to handle the output of such a large sensor. One of the most interesting is the chip's four-channel readout, which has been designed with dynamic range, rather than speed, in mind.

Four-channel readout

"Dynamic range is essentially signal-to-noise ratio, which is just signal divided by noise." the company said: "Going to a smaller pixel you get less signal so, to retain dynamic range, we need to drop noise."

"The 39MP chip was a two-channel readout design. This means each row was pulled down into the output register, then read out from either side of the chip to the amplifiers, before the next row could be pulled down. The 50MP is a four channel device - there are two registers, one for the odd pixels, the other for the even ones. Again, half go to the left and half go to the right.

"As you operate the amps faster and faster, you get more noise. This four-channel approach gave us more bandwidth, partly to deal with the extra information created by the extra pixels but also to allow us to run the amplifiers slower. On this chip there are four amplifiers running at 18Mhz, rather than two running at 24Mhz."

Pulse flush

Click-to-capture time is kept down by using a new pixel clearing technology Kodak has dubbed 'Pulse flush.' "Before you can read the output of a sensor, you have to make sure it's clear from any electrical noise that could be hanging around. Traditionally you had to read out all of the pixels, drop them down and through the output register. As you increase pixel count, this takes more and more time and also it takes power.

"What we've got in this design, in addition to the light sensitive area in each pixel, is a drain for anti-blooming draining. This is usually used to carry away excess voltage if the pixel is over-exposed, to stop that voltage over-flowing into neighboring pixels. We use that, in a process called 'Pulse flushing,' to drain all the pixels before each shot. This way the initial delay is measured in microseconds, rather than milliseconds."

Color accuracy

The other change in the new chip is the use of a new red pigment to increase color accuracy. "One of the things our customers liked about the last chip was the color accuracy but we thought we could do something to make it better. The new pigment shifts the absorption band 15 nm towards the blue, which increases the overlap between the red and green channels."

Increasing the overlap between channels helps the camera more accurately detect colors that fall between the two channels, meaning the new sensor should be better able to interpret yellow and orange tones.

Although Kodak refers to the chip as being the first product based on a new technology platform, it would not be drawn on whether this could include application on a DSLR scale. In addition to medium-format professional photography, the company said the sensor had been generating interest from aerial photography companies.

Press release:

World's First 50 Megapixel CCD Sensor Sets New Standard for Professional Photographers

ROCHESTER, N.Y., July 8, 2008 - Eastman Kodak Company (NYSE:EK) has achieved another breakthrough in its storied history of imaging technology innovation with the introduction of the world's first 50 million pixel CCD image sensor for professional photography.

At 50 million pixels, or megapixels, the sensor captures digital images with unprecedented resolution and detail. For instance, with a 50 megapixel camera, in an aerial photo of a field 1.5 miles across, you could detect an object about the size of a small notebook computer (1 foot by 1 foot).

What's more, the KODAK KAF-50100 Image Sensor features a newly designed pixel that is smaller in size than the pixel used in current products for this professional market. This new pixel also reduces "click-to-capture" time for improved camera response, lowers power consumption for improved battery life, and improves color fidelity without compromising on the benefits to be enjoyed from larger pixel sizes.

"Professional photographers need to capture ever-increasing image detail with higher camera performance, and that to drives us to develop new technologies and products to serve this important market," said Michael Miller, manager of Kodak's CCD Image Sensor Business, part of the company's Image Sensor Solutions group. "Kodak image sensors have been known as the professional imaging standard for years, and today's announcement reaffirms our dedication to provide industry-leading image sensors that give professional photographers a real competitive advantage."

The new Kodak sensor is the first to utilize the company's new KODAK TRUESENSE 6.0 micron Full Frame CCD Technology Platform, which increases both the resolution and camera performance available to photographers. Based on a newly designed 6.0 micron pixel, the platform provides increased data throughput for faster frame rate, a reduced "click to capture" time for improved camera response, lower power consumption for improved battery life, and improved color fidelity, while still retaining key performance parameters available from the larger, 6.8 micron pixel used in current products. With an 8176 x 6132 pixel array, the 50 million pixel sensor provides the highest resolution available in the popular 48 mm x 36 mm optical format used in medium format photography. The KAF-50100 is the latest addition to Kodak's family of full-frame CCD image sensors for the professional photography market. Engineering grade devices of the KAF-50100 are currently available, with volume production planned for Q4, 2008.