Color co-site sampling


Color co-site sampling
Chip, taken with a standard one-chip camera (left) and taken with a color co-site sampling camera.

Color co-site sampling is a system of photographic color sensing, wherein 4, 16 or 36 images are collected from the sensor and merged to form a single image. Each subsequent image physically moves the sensor by exactly one pixel, in order to collect R, G and B data for each pixel, known as Microscanning. This is a viable alternative to the typical Bayer filter array of pixels which returns a lower quality images with interpolated pixel colors.

Contents

Operation

Several images are captured and combined to a sharp resulting image. After the acquisition of each image a piezo mechanism moves the sensor by precisely the distance of one pixel and delivers the complete color information for each detail and with the same sharpness in all three color channels.

Microscanning is essential for the method. 4 (2x2), 16 (4x4) or 36 (6x6) shots can be used for improved color reproduction.

  • Advantages
    • Higher resolution possible in comparison with the basic CCD pixel count
    • No color interpolation required
    • Better sensitivity than a three-chip camera
    • Live color image possible at the basic CCD sensor's resolution
    • Only one color sensor required
  • Disadvantages
    • Stable imaging conditions required due to microscanning
    • Longer acquisition times because of multiple exposures
During the acquisition, the sensor is moved by the distance of one pixel. Thus every pixel is scanned at least once in all three colors.


Comparison to Bayer filter

The color CCD is moved to 2x2 positions, sampling the color information of the corresponding pixel at each location of the sensor.

With standard digital cameras, color images are acquired with only one sensor (see CCD and CMOS sensor). Each pixel of the sensor is sensitive to just one of the three basic colors. For each single pixel on the CCD only one third of the required information is provided and two thirds are missing, as at least three monochrome pixels would be necessary for one color pixel. As only one image is acquired, the missing color information is determined by the interpolation. In current cameras sophisticated interpolation algorithms are used to reconstruct the color information(see filter mosaics, interpolation, and aliasing), so the reduction in the "color" resolution can turn out to be better than the expected one third. Because of the interpolation, however, unwanted side-effect artifacts, such as color Moire patterns or false colored edges, can occur.

  • Advantages
    • R, G, B in one exposure
    • Color live image and dynamic scenes possible
  • Disadvantages
    • Color interpolation
    • Reduced spatial resolution
    • Susceptible to color errors

References

External links


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Bayer filter — The Bayer arrangement of color filters on the pixel array of an image sensor …   Wikipedia

  • Digital camera — Digicam redirects here. For the military camouflauge method using micropatterns, see Military camouflage#Digital camouflauge. A digital camera (or digicam) is a camera that takes video or still photographs, or both, digitally by recording images… …   Wikipedia

  • Microscanning — is a method for increasing resolution of digital cameras. With the color co site sampling identically colored pixels in several frames of the specimen, obtained by moving the sensor with a piezo mechanism in a regular raster, are combined to a… …   Wikipedia

  • Charge-coupled device — A specially developed CCD used for ultraviolet imaging in a wire bonded package. A charge coupled device (CCD) is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for… …   Wikipedia

  • Image sensor — A CCD image sensor on a flexible circuit board …   Wikipedia

  • H.264/MPEG-4 AVC — H.264 is a standard for video compression. It is also known as MPEG 4 Part 10, or MPEG 4 AVC (for Advanced Video Coding). As of 2008, it is the latest block oriented motion compensation based codec standard developed by the ITU T Video Coding… …   Wikipedia

  • Flashline Mars Arctic Research Station — Flashline Mars Arctic Research Station …   Wikipedia

  • Subcarrier — A subcarrier is a separate analog or digital signal carried on a main radio transmission, which carries extra information such as voice or data. More technically, it is an already modulated signal, which is then modulated into another signal of… …   Wikipedia

  • RCA — Infobox Defunct Company company name = RCA Corporation company slogan = The most trusted name in electronics. fate = Taken over by General Electric and broken up successor = foundation = 1919 defunct = 1988 location = New York, USA… …   Wikipedia

  • Pixel — This article is about the picture element. For other uses, see Pixel (disambiguation). This example shows an image with a portion greatly enlarged, in which the individual pixels are rendered as little squares and can easily be seen …   Wikipedia