Limitations of linearity and quantum efficiency . How it operates Light from telescope imaged on an array of photosensitive silicon pixels arranged in a grid on a chip. Electrons released and stored in each pixel.
Process is repeated until each row of pixels has been converted into numbers.
This is illustrated on the image below, showing the image of a star forming on a chip and being transferred out, row by row, into a computer. The result is a data file with the pixel values stored as numbers proportional to the amount of light that struck the chip. These can be displayed as images on a computer screen. Number of Pixels, dimensions of the CCD chip. Ease of manipulation of electronic data files as compared with film.