There's been quite a debate going on lately about CCD resolution and the color interpolation that's performed in firmware. Can you shed some light upon the method that Nikon uses to extract color information from the CCD?

-- Tara (tariah@mediaone.net), March 17, 2000

Answers

With the exception of scanback digital cameras, all digital still cameras use some form of color interpolation. Most (with the exception of the Fuji S-1 and Finepix 4700-which use a different method of color and image size interpolation/extrapolation) use what is known as a Beyer array.

CCD's read gray scale. Red Green and Blue filters are placed over each pixel. (some cameras use Cyan, Magenta and Yellow filters or an addition of Green).

The pattern in a Beyer array is as follows (Red=R, Green=Green, and B=Blue):

RGRGRGRGRGR GBGBGBGBGBG RGRGRGRGRGR GBGBGBGBGBG

and so on.

As you can see, 25% of pixels are red, 25% are blue and 50% are green.

The human eye is most sensitive to green-and it helps define contrast.

As such you now have to figure out from the figure above how to create a red, green and blue layer from 1 intertwined layer...

RRRRRRRRRRRR RRRRRRRRRRRR RRRRRRRRRRRR RRRRRRRRRRRR

GGGGGGGGGGGG GGGGGGGGGGGG GGGGGGGGGGGG GGGGGGGGGGGG

BBBBBBBBBBBB BBBBBBBBBBBB BBBBBBBBBBBB BBBBBBBBBBBB

Together creating an RGB image in full 24 bit color.

The key is determining color from the nearest like neighbors and determing the proper value.

At Nikon we use the best algorithms we have developed and our knowledge of color, light and optics. Also-our electronics are based on our white balance and overall proper exposure. All this together results in the most accurate color in most lighting conditions.

Hope that explains it!

Michael

-- Mike Rubin, Product Marketing Manager Nikon (web@imaging-resource.com), March 23, 2000.