STV-5410-R01 STMICROELECTRONICS [STMicroelectronics], STV-5410-R01 Datasheet - Page 20

• Manufacturer Part Number: STV-5410-R01
• Description: Mono and Colour Digital Video CMOS Image Sensors
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

VV5410 & VV6410
Dark Offset Cancellation
5.
Dark Offset Cancellation
VV5410/VV6410 performs dark line offset cancellation as well as black line offset cancellation. A dark line is shielded from
incident light by an opaque material such as metal 3 (as an example) but these lines will be exposed to incident light for the same
length of time as the visible pixels. If the dark pixels are completely shielded from light then no incident light should reach the
pixels and the pixels will produce the same digital code as the black pixels, i.e. 128 internally (therefore 64 externally). The
algorithm used to calculate the dark offset cancellation is identical to that used to calculate the black offset cancellation, however
the dark algorithm does assume that the dark pixels have already been black corrected therefore the target dark average is 64
thus the dark offset cancellation is 0 by default.
The dark offset cancellation algorithm is configured by the dark offset cancellation setup register, [46], see subsubsection 9.5.3.
The only parameter in this that is different from the corresponding table that configures the black offset cancellation algorithm is
the control bit, [bit2], that determines the number of dark lines that are to be used by the cancellation algorithm. It is possible to
select half of the total number of available dark lines to be used to calculate the dark offset cancellation setting. When the former
is selected the dark lines used by the algorithm are always preceeded by another dark line, thereby giving extra immunity from
damaging edge effects that may occur on lines close to the edge of the shield material.
It should be noted that the black and dark offset cancellation are completely independent. For example it is possible for the user
to select internal automatic black offset cancellation but to opt for no dark offset cancellation or indeed choose to perform the dark
offset cancellation externally.
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