Christening ‘Color and Light’

The invention of the Foveon X3 Direct Image Sensor resulted from the research of Carver Mead, a professor at the California Institute of Technology (Caltech). An authority in physics and information technology, having handled a great deal of fundamental research in those fields, he poured his energy into the research of modeling the various abilities of people through the use of semi-conductors. Before long, he developed a neural network to simulate people’s thoughts and sensory patterns where part of that research became the beginning of his research into image sensors. As one of the founding members of Foveon, Rudy Guttosh looks back at the development’s whole story and what makes the sensor special.

“Mead’s research was a venture that started in August 1997 based on the support from Synaptic and National Semiconductor, prominent companies in the Silicon Valley region of USA. Foveon, Inc. was named after the anatomical term for the central area inside the human retina where eyesight and color is most acute, ‘Foveon Centralis’. It was clear from the outset that here was a team with a strong awareness of advanced visual functions that aspired to develop an innovative, high performance sensor.

A Fitting Sensor for Photographers

From the very beginning of Foveon, there was a gathering of highly experienced and excellent engineers in the imaging field who also happened to be passionate about photography.

“Already around at the time was the CCD sensor. It was a technically sophisticated sensor with low noise and a wide dynamic range that had come about after a long period of development. But there were quite a few engineers who noticed problems with the images generated by the conventional system, such as how the low-pass filter reduced the array of color filters that read color information, and the false colors that would appear from the subject. For the team of engineers assembled at Foveon, it was a major objective to develop the unique CMOS sensor that could read the good light and colors in the background and convert them to quality digital imagery.

“The first prototype emerged I believe a year and a half after we set out on this project with what we called a ‘3-layered prism camera system’. We placed three of our large CMOS monochrome sensors inside a camera where a beam of light passed through a prism and dispersed light through 3 color filters of red (R), green (G) and blue (B) to produce an image on a sensor. However, to produce a 3-layered prism camera was costly as having 3 image sensors, an expensive prism that separate color, and the advanced technology to fix them together was the key. For Foveon to realize a sensor that fulfills true image quality that is sought after, a completely new technology had to be built.”

3 Primary Colors in 1 Pixel.

“However also, as soon as we reached this stage of development, we knew instantly that with this unique technology, we had designs on the professional equipment market that would respond to the needs of photographers”. Also, having abandoned the 3-layered prism camera due to practical concerns, the prerogative in the early stage of development for Dick Merrill^*1, leader of the project, was to focus on patenting a device that captured all of the RGB in one pixel location.”

“After graduating from university, he became engaged in advanced research in the semiconductor field at the research facility of Thomas J. Watson at IBM and at National Semiconductor. He was an engineer with an abundance of experience. At the same time, being a person with a gift for art and a passionate photographer, he poured his passion to develop an image sensor to pursue suitable performance for artistic expression after joining Foveon, and frequently went around the west side of America to conduct field tests.

Merrill was a man with a unique history behind him and blessed with a myriad of talents. Ask anyone involved in this unprecedented development to integrate leading advanced technology with art, and they would say that Merrill’s ideas and attitude were essential to building this innovative full image sensor technology. “With a mini-van loaded with test equipment, Merrill went around the highways in pursuit of the ‘perfect light’ of dusk and dawn. He literally was a ‘special engineer’ we remember to this day as the personification of the ‘camera for artists’”.

The birth of the Foveon X3 Direct Image Sensor.

The “device” Merrill invented certainly read all of the RGB in one pixel location, but the technological challenge as to how to generate quality images from the light information had yet to be addressed.

“The man to offer the solution to this was our chief of development at Foveon, Dick Lyon, also known as the ‘other Dick’ ^*2. Besides being an expert on signal technology, as a passionate fan of photography, he had a strong interest in the technology Merrill had worked on. The physical characteristics of silicon enable wavelengths of light to be absorbed around the surface. Though it is a known fact among semi-conductor manufacturers that longer and longer wavelengths of light would be absorbed with an increase in depth, to convert the appropriate image signals to generate photographs required additional technological innovations.”

“Dick Lyon conducted research into the absorption capabilities of silicon and the characteristics of RGB wavelengths in the spectrum, finally coming to the theory of a method where through 3 photo diodes; color is captured within the particular depths of each pixel location. He was convinced that if a method of vertical color separation could be ensured, a photographer’s high expectations of color reproduction could be met. With the utilization of the vertical physical properties of silicon and applying them to image sensors, the 3-layered RGB structure (2048 x 2048 pixels x 3 layers), what became ‘the world’s first 3-layered CMOS image sensor’ was put to the test.” I remember the nerves and anxiety all around at the moment of testing to capture an image.

“When Lyon passed the RAW image data through an image handling pipeline, there was a gasp from everyone in the room. To finally obtain the same color quality as that prism camera with 3 sensors with a single, diminutive 3-layered chip was the moment the ‘Foveon X3 direct image sensor’ was born.

The Meeting of Foveon and SIGMA.

“The development team had soon developed a number of prototypes. Merrill never let go of the camera, even during breaks, and repeatedly conducted tests at a variety of locations. The performance of the test camera was to his satisfaction and confidence grew in its color reproduction abilities and dynamic range. However, to put this into practical use, it was essential to have a partner that shared the same philosophy and vision as us and was able to manufacture with its principles in mind.”

“Mead had searched for a company that would buy this technology way before building the sensor technology. They made an appearance at the biannual ‘photokina’ in Cologne, Germany in September 2009 where they exhibited the ‘prototype’ (prism camera). It was here that we met the founder of SIGMA and president at the time, the late Michihiro Yamaki.”

“Although SIGMA had already produced a silver salt film camera at the time, Yamaki wanted to bring the digital capture technology employed in high-end digital cameras in the photojournalism world to the general market. He was certain that sooner or later that there would be a shift in the use of film. Also, the race in sensor development and the optical performance of lenses had intensified. He predicted the success or failure of optical manufacturers would be determined by this and had to find which path SIGMA would take from hereafter.”

“Despite Foveon not exhibiting a demonstration model at that year Photokina, Yamaki strongly felt that with this technology, the originality and possibilities that flowed out of the outstanding image quality would mark a fresh departure from other companies. He visited Foveon shortly after and tried out the prototype Foveon X3 image sensor by taking some images himself. As soon as he saw the results, he made the decision to produce cameras installed with Foveon technology.”

The decision for 100% Foveon Subsidiary

The year was 2008. SIGMA had finally made Foveon Inc. and with it, its Foveon X3 direct image sensor into a subsidiary of the company. For SIGMA, general optical machinery manufacturers who manufactures nearly all in-house and were determined to continue to supply quality products to the highest industry standards, to develop its own sensor within their own company was a clear sign of unwavering resolve. As much as anything, within the challenges faced with their shared photography and business philosophy, it could be said that the inevitable route that SIGMA and Foveon had taken has intertwined.

With an unknown but outstanding sense of resolution, gradation and warmth of color, a certain sense of substance had by the Foveon and a solid ‘body’, felt in the image quality. It is true image quality derived from the natural light above Earth. It has been 20 years since Foveon was established and 15 years since working alongside SIGMA. The APS-C size and medium class image quality offered by Foveon has carved a strong impression into the hearts and minds of those who love photography.

The Meme of Foveon and SIGMA

“There are images that only Foveon is capable of expressing. A curiosity to try the Foveon out for yourself. Sublime color reproduction. Overwhelmingly warm gradation. The width of the dynamic range derived from the fundamentals of the sensor. A ‘film-like’ quality that clings to the image data. It is these characteristics that set us apart from cameras that accurately copy the image. What is said to be Foveon is the patience to keep getting closer to recreating one’s scene pictured in their mind.

“To ask why Foveon continues to charm the many ‘connoisseurs’ who seek expression, it has to be the character of Foveon, the rich detail from the sense of resolution provided by the 3-layered vertical structure, similar to that of the color sensitive layer of film. Taking a look at the chart explaining the spectral characteristics of the Foveon sensor, the red, blue and green wavelengths overlap with each band where it is clear to see that enough information reaches every band. The source of the Foveon is due to the traits of the ‘Panchromatic’ that is able to read information in the middle band that ‘simple’ colors are unable to share. This is what gives the Foveon its distinctive outstanding image quality.

The icon of SIGMA, Foveon has been installed in the SD9/SD10 (1st generation), SD14/SD15 (2nd generation) toward the 3rd generation “Merrill”, named after Dick Merrill, the personification of innovative technology and passionate manufacturing. And now with the radical “Quattro”, conceptualized as a “camera for artists”, boundaries are being pushed to this day.

“The Quattro sensor is steeped with the Meme of Foveon and SIGMA. Like being transported into an image, it retains the ‘Foveon Look’, that rich and high quality “Panchromatic” character derived from the principles of the sensor, as well as an abundance of detail thanks to the high-resolution. Even with higher resolution, the increase in data is controlled, and with the wide range of improvements for better handling, the sensor continues to move forward.”