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Kodak Image Sensor Solutions has today announced a new Color Filter Array (CFA) layout (and image processing path) as an alternative to the widely used Bayer pattern which should provide higher sensitivity. This new layout features one 'panchromatic pixel' (monochrome) to every colored pixel (red, green or blue) and there are three proposed layouts. Kodak ISS are presenting this as a technology solution which can be applied to any size, megapixel count or type (CCD / CMOS) of sensor. Kodak claim a one to two stop improvement in sensitivity, the tradeoff is of course color resolution which is effectively a quarter of the traditional Bayer pattern. This interesting development will of course only be proven when we see it actually implemented and we can compare it to traditional Bayer.
Next Generation Color Filter Patterns Deliver Higher Quality Photos Under Low-Light Conditions
ROCHESTER, N.Y., June 14, 2007 – Eastman Kodak Company (NYSE:EK) today introduced a groundbreaking advancement in image sensor technology that will help make dark, blurry digital photos a thing of the past.
Kodak’s new sensor technology provides a significant increase in sensitivity to light when compared to current sensor designs. With this new technology, users will realize a 2x to 4x increase in sensitivity (from one to two photographic stops), which will improve performance when taking pictures under low light and reduce motion blur when imaging moving subjects. In addition, this technology enables the design of smaller pixels (leading to higher resolutions in a given optical format) while retaining imaging performance.
This breakthrough advances an existing Kodak technology that has become a standard in digital imaging. Today, the design of almost all color image sensors is based on the “Bayer Pattern,” an arrangement of red, green, and blue pixels that was first developed by Kodak Scientist Dr. Bryce Bayer in 1976. In this design, half of the pixels on the sensor are used to collect green light, with the remaining pixels split evenly between sensitivity to red and blue light. After exposure, software reconstructs a full color signal for each pixel in the final image.
Kodak’s new proprietary technology builds on the existing Bayer Pattern by adding panchromatic, or “clear” pixels to the red, green, and blue pixels already on the sensor. Since these pixels are sensitive to all wavelengths of visible light, they collect a significantly higher proportion of the light striking the sensor. The remaining red, green, and blue pixels are then used to record the color information of the scene.
To reconstruct a full color image, Kodak has also developed new software algorithms specifically designed to work with the raw data generated from these new image sensors. These sophisticated algorithms use the more sensitive panchromatic pixels to act as the luminance channel of the final image, and derive chrominance information from the color pixels on the sensor. Leveraging over 30 years of Kodak image science, these new algorithms support the increased sensitivity provided by these new pixel patterns, while retaining the overall image quality and color fidelity required by customers.
“This represents a new generation of image sensor technology and addresses one of the great challenges facing our industry – how to capture crisp, clear digital images in a poorly lit environment,” said Chris McNiffe, General Manager of Kodak’s Image Sensor Solutions group. “This is a truly innovative approach to improving digital photography in all forms, and it highlights Kodak’s unique ability to deliver advanced digital technologies that really make a difference to the consumer.”
Kodak is beginning to work with a number of leading companies to implement this new technology in system-wide solutions and to streamline the design-in process.
Initially, Kodak expects to develop CMOS sensors using this new technology consumer markets such as digital still cameras and camera phones. As the technology is appropriate for use with both CCD and CMOS image sensors, however, its use can be expanded across Kodak’s full portfolio of image sensors, including products targeted to applied imaging markets such as industrial and scientific imaging. The first Kodak sensor to use this technology is expected to be available for sampling in the first quarter of 2008.
For additional information regarding this technology, please contact Image Sensor Solutions, Eastman Kodak Company at (585) 722-4385 or by email at firstname.lastname@example.org. For more information on Kodak’s entire image sensor product line, please visit www.kodak.com/go/imagers.
Today, almost all color image sensors are designed using the “Bayer Pattern,” an arrangement of red, green, and blue (RGB) pixels that was first developed by Kodak scientist Dr. Bryce Bayer in 1976. A Bayer filter mosaic is a color filter array (CFA) for arranging RGB color filters on a square grid of photosensors. The term derives from the name of its inventor, Dr. Bryce E. Bayer of Eastman Kodak, and refers to a particular arrangement of color filters used in most single-chip digital image sensors to create a color image.
In this design, half of the pixels on the sensor are used to collect green light, with the remaining pixels evenly split between sensitivity to red and blue light. After exposure, software is used to reconstruct a full RGB image at each pixel in the final image. This design is currently the de facto standard for generating color images with a single image sensor, and is widely used throughout the industry.
The new approach builds upon the standard Bayer pattern by adding panchromatic pixels – pixels that are sensitive to all visible wavelengths – to the RGB pixels present on the sensor. Since no wavelengths of visible light are excluded, these panchromatic pixels allow a (black and white) image to be detected with high sensitivity. The remaining RGB pixels present on the sensor are then used to collect color information, which is combined with the information from the pan pixels to generate the final image.
Note that this is not one single pattern, but a concept – the use of panchromatic pixels to increase the overall sensitivity of the sensor. Depending on the application, different patterns may be more appropriate for use. For example, one natural trade-off is the balance between the sensor’s overall sensitivity (via the pan pixels) and how well the sensor collects color information (via the RGB pixels). The highest sensitivity would come from a sensor composed only of pan pixels, but would provide no color information. By changing the ratio of pan to RGB pixels, applications with different sensitivity and color needs can be best accommodated. Other considerations might be the ease of image reconstruction (i.e., patterns optimized for applications where reduced processing power is available), or for backward compatibility with video subsystems (where the raw data from the sensor easily decimates to a standard Bayer RGB pattern for input into video processors).
This technology increases the overall sensitivity of the sensor, as more of the photons striking the sensor are collected and used to generate the final image. This provides an increase in the photographic speed of the sensor, which can be used to improve performance when imaging under low light, enable faster shutter speeds (to reduce motion blur when imaging moving subjects), or the design of smaller pixels (leading to higher resolutions in a given optical format) while retaining performance.