The ccd Cell (charge coupled device) © 2007

Function of a single cell
A single cell measures the intensity of light. It puts out a voltage proportional to the amount of light hitting it.

It does not understand the concept of color.

Think of it as a pressure gauge, it measures the intensity of light, but cannot differentiate the wavelength.

28 = 256
216 = 65536

**animation 8.6 mb

The resolution chart at the bottom of the right column represents the typical number values that the electronics can differentiate from the sensor. This is a function of what is called the A/D (analog to digital) converter. If the ccd cell put out 0V (zero) voltage with no light and a maximum of 5V with maximum light, then it would break this voltage range down to either 256 levels or 65536 levels based on the true intensity. It would be 8 bit or 16 bit resolution.

--------- OK, time to fess up! ----------

In this animation I theoretically place filters in front of the light source, they would actually block certain wavelengths of the white light and thus lower the intensity (compared with full white light). I decided to present this "white lie" to better illustrate the point I am trying to make.

In the real world, the light hitting the ccd cell would come from reflected sunlight from objects. The object would determine the color of the light it reflects and would not "stand between" the sensor and the source. The sensor would be oblivious to the color, it would simply measure the intensity.

I used this little subterfuge to illustrate the hue neutrality of the sensor. If the red and green filters were of equal strength then the sensor would not differentiate their resultant voltages based on their color.