Split Filter Selection; Figure 28: C Shaping Filter Selection No. 4 To 13 In Table 11; Figure 29: C Shaping Filter No. 14 To 18 In Table 11 - Analog Devices ADV7850 Hardware Manual

ADV7850
Figure 28: C Shaping Filter Selection No. 4 to 13 in Table 11
Figure 29: C Shaping Filter No. 14 to 18 in Table 11
6.10

SPLIT FILTER SELECTION

The ADV7850 offers a dynamic, pixel-by-pixel split filter alpha blending between a fixed, wide split filter and the split filter selected in the
split filter selection register. The alpha blending determines if the region being combed would benefit most from a wide or a narrow split
filter. The decision is based on splitting the picture into areas where a wide split filter is useable (content with very low vertical change and
areas with low/moderate frequency color) and everywhere else (areas with high detail horizontally and vertically). A narrow split filter
selection gives better performance on diagonal lines, but leaves more dot crawl in the final output image. The opposite is true for selecting
a wide bandwidth split filter.
The split filter selection register allows one of six split filters to be chosen, thereby giving the user control over the narrow split filter that is
used in the alpha blending. The filter selection is independent of the input format since the decoder is burst locked and effectively changes
its internal operating clock based on the color burst frequency. Therefore, the characteristics of the selected filter will scale with the Fsc
frequency of the input signal. Figure 30 shows the frequency responses of the selectable split filters.
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