A number of filter options are available to improve the consistency of the results by removing the information present in one of the two video fields to prevent a particle appearing to be in two places at once. These filters are applied to the entire buffer. Note that if the frame spacing is set to 1 field then these filters will have no effect except that a choice of E or O will force line duplication whereas 0 or 1 will force line averaging to be used to fill in the missing information for each half of the interlace as it is processed.
The even numbered lines on the entire buffer are duplicated into the odd numbered lines. This effectively halves the vertical resolution. This filter may be desirable when the fluid velocity is sufficiently high for the two halves of the interlace to contain significantly different data. For image capture from freeze frame, the Odd line filter should be used as the odd lines appear to be more robust to timing errors.
This option suppresses any filtering (other than that required implicitly by any part of the tracking routine).
The even numbered lines on the entire buffer are duplicated into the even numbered lines. This effectively halves the vertical resolution. This filter may be desirable when operating in manual mode from freeze frame or when the fluid velocity is sufficiently high for the two halves of the interlace to contain significantly different data.
This option is similar to E except that rather than the odd numbered lines being replaced by a copy of the preceding even numbered line, they are replaced by an average of the preceding and subsequent even numbered lines.
This option is similar to O and 0 except that rather than the even numbered lines being replaced by a copy of the following odd numbered line, they are replaced by an average of the preceding and subsequent odd numbered lines.