Charge-Coupled-Device-Sensors capture the charges produced by light. Line by line the charges are transported through the sensor to an output node where they are converted to an analogue signal.
Complementary-Metal-Oxide-Semiconductor-Sensors also collect photogenerated charge. Each single pixel has an integrated complementary transistor circuit which amplifies the signal and assigns a digital value.
This technology enables the integration of complex circuitry on the sensor. If camera functions are implemented, each pixel can be optimised regarding e.g. brightness, range of contrast and white balance.
Smear effect means that a bright vertical line originating from a bright light source appears in the image, this happens especially with back lighting.
Because of the way the data is read out, this effect only occurs with CCD sensors. The charges on the sensor are shifted line by line to the bottom of the sensor, where they are read out consecutively. During the movement of lines across the sensor, the electrical charges passing the bright light source are exposed and so raised. Thereby a vertical, white stripe is formed within the picture.
With CMOS sensors this effect can not happen as the charge is read out directly from the pixel itself.
The 'blooming' effect only appears with CCD sensors as well.
By strong light exposure within a small pixel area more electric charge is produced than can be held by just one pixel. The excess charge is emitted to the adjoining pixels. Likewise these pixels can only hold a certain quantity of charges and so emit the surplus again. This leads to a saturation of charges on the sensor and so to overexposed picture areas.