Decomposing light into frequency spectrum Light hits a charge coupled element. The wavelength of the light somehow is translated into a color picture. Where can I learn about methods (algorithms) to decompose light hitting a CCD into frequency spectrum? 
 A: A color CCD is made of a monochrom CCD Sensor and an array of filters. The common Bayer pattern is a pattern of 2 green, a blue and a red filter. The filters transmits light on your broad band CCD sensor. A color CCD already does some spectral analysis.
The four physical pixels are read into RGB channels of one color pixel.
If you want to see the spectrum of color than see a histogram of RGB channels in your favorite graphics tool.
E.g. the green bandpassfilter allows transmittance of several light frequencies $\nu = \frac{c}{\lambda}$ in the green and possibly overlapping with blue and red filters. Usually the wavelength $\lambda$ is used to define the color of the light. 
This relation for visible light is visualized in the spectrum of light. Imagine the intensity on the green pixel is composed of all light transmitted through the green filter. It is not possible to tell "which green" frequency caused the signal on the green pixel. This information about the frequency spectrum is lost.
The CCD just delivers electrons and firmware translates it to a digital value. A pure CCD can not decompose the measured intensity. The information is lost. 
A: I guess that the CCD sensor already gives you data decomposed into red, green and blue, or more colors if it's built for scientific purposes. In any case, the sensor does the decomposition itself, not you (or a computer).
