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White flecks
Although the CMOS image sensors are produced with high-precision technologies, fine white flecks may be
generated on the screen in rare cases, caused by natural and/or artificial radition, which causes a “false ex-
posure” on the image sensor. The shape of these spots may vary from dots to lines or other, sometimes irregular
shapes. These spots occur in random locations of the image, last only for a single frame and are more visible in
dark images. This is a principle issue of all image sensors and not a malfunction.
The white flecks especially tend to be seen in the following cases:
• when operating at a high ambient temperature
• when you have raised the gain (sensitivity)
The white flecks may be reduced by turning the camera off, then on again.
Aliasing
When fine patterns, stripes, or lines are shot, they may appear jagged or flicker. Aliasing refers to the effect
produced when a signal is imperfectly reconstructed from the original signal. Aliasing occurs when a
signal is not sampled at a high enough frequency to create an accurate representation. This effect is shown in
the following example of a sinusoidal function:
In this example, the dots represent the sampled data and the curve represents the original signal. Because there
are too few sampled data points, the resulting pattern produced by the sampled data is a poor representation of
the original.
The following occurrences that may appear in images are specific to CMOS (Complementary Metal Oxide
Semiconductor) image sensors. They do not indicate malfunctions.
APPENDIX C - CMOS IMAGE SENSORS CHARACTERISTICS
