An image processing system ready for higher resolution.
Outstanding performance, next-level image quality.

With its three-layer structure, the Foveon X3 Quattro direct image sensor captures all of the information carried by visible light. This film-like capture system offers rich gradations and color and truly distinctive image quality. Optimized to match the enhanced resolution and other characteristics of the image data, the image processing system of the new SIGMA sd Quattro leverages the outstanding fundamental functions of the camera while taking overall image quality to the next level.

Two sensor sizes available The SIGMA sd Quattro incorporates an APS-C size sensor for outstanding medium format level image quality,
while the SIGMA sd Quattro H features a new APS-H size sensor for
51 megapixel-equivalent ultra-high image quality.

Other cameras typically use a single-layer photo sensor covered by a Bayer filter mosaic, which comprises 50% green, 25% blue, and 25% red squares. In contrast, the Foveon X3 Quattro direct image sensor uses no low-pass filter and is able to capture 100% of the data for blue, green, and red in each of its three layers. Due to this unique structure, the Foveon X3 Quattro direct image sensor can generate up to twice the resolution data of sensors using a Bayer filter. The SIGMA sd Quattro has an APS-C-size sensor with 19.6 megapixels in its top layer, giving it an equivalent total of approximately 39 megapixels and the outstanding image quality expected of a medium format camera. The SIGMA sd Quattro H features a newly developed APS-H size sensor (26.7 x 17.9mm) with 25.5 megapixels in its top layer for an equivalent total of approximately 51 megapixels. This larger sensor takes Foveon image quality to the next level, delivering more detailed images than ever before.

Foveon direct image sensor The world’s only image capture system to use
vertical color separation technology

Starting with our very first digital camera, we have featured the Foveon direct image sensor, which offers radically better image quality than any other sensor available. Leveraging the light absorption characteristics of silicon, the sensor comprises three layers of photodiodes, each at a different depth within the silicon and each corresponding to a different RGB color. Since it is the only sensor to use this superior vertical color separation technology, it is also the world’s only direct image sensor.

Almost all other image sensors are mosaic sensors, which use an array of RGB color filters in a single horizontal plane to capture color information. Each pixel is assigned only one of the three colors and cannot capture all three colors at once. In contrast, the Foveon direct image sensor captures color vertically, recording hue, value, and chroma accurately and completely for each pixel.

In the Foveon direct image sensor, there are no color filters which would cause a loss of information transmitted by light. Moreover, there is no low-pass filter needed to correct the interference caused by a color filter array. Finally, unlike the data from other sensors, which requires artificial interpolation to “fill in” missing colors, the data from the Foveon direct image sensor is complete for every single pixel and requires no interpolation. The unique technological principle of this sensor produces consistently outstanding image quality.

Newly developed Foveon X3 Quattro
direct image sensor Now featuring 39 megapixel-equivalent ultrahigh resolution

Capturing the information transmitted by light vertically instead of horizontally, the full-color image capture system of the Foveon direct image sensor is the only one of its kind in the world. This system makes possible the sensor’s full-bodied image quality, which is characterized by rich tone and gradation and texture that one can almost touch.

The newly developed Foveon X3 Quattro is the latest generation of this unique sensor. While retaining the distinctive characteristics of its predecessors, it offers an even higher level of image quality. Resolution is 30% higher, and its noise characteristics are further enhanced.

The new sensor structure features a ratio 1:1:4 for the number of red, green, and blue megapixels, respectively. The top layer captures luminance and color information, while the bottom two layers capture color information only. This unique structure prevents the deterioration of the signal-to-noise ratio that is typically associated with an ultrahigh megapixel count. At the same time, it makes possible high-speed data processing required for faithful color replication. Able to maintain the same exacting standard of image quality while increasing resolution and enhancing noise characteristics, this 1:1:4 solution was the inspiration for the name of the current generation of Foveon sensor: “Quattro.”

The new 1:1:4 structure (bottom 1: middle 1: top 4) offers higher resolution
that is equivalent to 39 megapixels for conventional color filter array sensors.
In addition to this ultra-high resolution, the sensor offers enhanced noise characteristics
and faster processing of high-volume image data.

The difference between the Foveon X3 Quattro direct image sensor and a conventional color filter array sensor (Bayer filter sensor)

The Foveon X3 Quattro leverages the selective absorption of light by silicon: shorter wavelengths penetrate less deeply into the element, whereas longer wavelengths penetrate more deeply. Comprising three silicon layers for each of the three primary colors of light (blue, green, and red), the Foveon X3 Quattro sensor vertically captures full color information for every single pixel. Unlike a conventional sensor, this full-color capture system requires no color interpolation at the data processing stage. Having complete color information for every pixel location makes possible highly precise and delicate resolution and color expression.

The special characteristics of the 1:1:4 structure

High resolution is a necessary condition of outstanding image quality. At the same time, adding megapixels to increase resolution also results in a bloated image file size. The risk of file bloat is especially pertinent in the case of image data in the .raw format containing RGB information for every pixel location.

As the spectroscopic chart indicates, the Foveon X3 Quattro direct image sensor is able to detect a broad range of light wavelengths. We came upon the idea of having the top/blue layer capture luminance information, which in turn led us to the idea of the 1:1:4 structure. While the top layer captures both luminance and color information, the middle and bottom layers with their larger surface area capture color information only. During the image data processing stage, the luminance data captured in the top layer is applied to the top, middle, and bottom layers, resulting in luminance and color data for each individual pixel.

The Foveon X3 Quattro direct image sensor retains the three-layer vertical color capture of previous Foveon sensors while featuring the new ability to capture luminance information in the top layer and apply that information to the middle and bottom layers. This new structure has been the key to preventing file bloat, which may eventually have proved a problem for the 1:1:1 structure of the previous generation of Foveon sensors.

Dual TRUE III for high-speed processing
of high-volume data

TRUE (Three-layer Responsive Ultimate Engine) III is the dedicated image processing engine for the Foveon X3 Quattro direct image sensor. SIGMA’s original algorithm processes data without loss of color detail or other image degeneration to deliver extremely detailed image expression with a noticeable 3D pop. In addition, by using two separate TRUE III engines, the camera is able to process data from the Foveon X3 Quattro direct image sensor at extremely high speed.

Combination of two AF detection methods Speed versus focusing performance:
two AF detection methods available for smoother and more accurate autofocusing.

Phase detection AF is superior for speed performance, while contract detection AF is superior for focusing accuracy. Combining these two methods in a single system delivers AF that is fast and precise at the same time. In addition, this approach to autofocus takes full advantage of the characteristics of high-performance lenses. The Single AF mode is optimal for everyday photography, while the Continuous AF mode is optimal for focusing on a moving object. In the latter mode, pressing the shutter button halfway causes autofocus to operate continuously, while Movement Prediction AF operates at the same time for more accurate autofocusing. A variety of other AF modes are also available. 9-Point Selection AF mode allows the user to select among nine focus frames. Free Movement AF mode allows the user to select the focus frame with high precision. Face Detection AF mode detects human faces and prioritizes focusing on them. The AF assist light incorporated in the camera body makes possible the use of AF even in low-light conditions.

New Super-Fine Detail exposure mode New SFD mode for lower-noise, higher-definition images

The new Super-Fine Detail (SFD) exposure mode brings out the full performance of the Foveon X3 Quattro direct image sensor. One push of the shutter generates seven different exposures, creating RAW data in the X3I file format. Using this data with the SIGMA Photo Pro software package, the photographer can create noiseless images with an extensive dynamic range. With this new mode, the more detailed imaging potential of the Foveon X3 Quattro direct image sensor is fully leveraged. From each X3I file, individual X3F files may also be generated. The value of SFD exposure mode is especially apparent in studio photography.

Note: To prevent camera shake, SIGMA recommends the use of a tripod.

Continuous shooting of up to
12 images in RAW format

The DDR III high-speed, high-volume memory is approximately twice the capacity of that of the SIGMA dp Quattro. This allows the SIGMA sd Quattro to capture up to 12RAW images (X3F files) in High size during continuous shooting (SIGMA sd Quattro H: up to 8 images). As a further option, when Low size is used, the SIGMA sd Quattro offers a continuous shooting of up to 24 images (SIGMA sd Quattro H: up to 16 images).