Video and Vision Processing Suite Intel® FPGA IP User Guide

ID 683329
Date 8/08/2022

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17.3.5. Result to Output Data Type Conversion

After calculation, the FIR Filter IP converts the fixed-point type of the results to the integer data type of the output.
  1. Scales result. Scaling quickly increases the color depth of the output. You can shift the binary point right –16 to +16 places. The IP implements scaling as a simple shift operation so it does not require multipliers.
  2. Removes fractional bits. If any fractional bits exist, you can choose to remove them through these methods:
    • Truncate to integer. The IP removes fractional bits from the data; equivalent to rounding towards negative infinity.
    • Round half up. The IP rounds up to the nearest integer. If the fractional bits equal 0.5, rounding is towards positive infinity.
    • Round half even. The IP rounds to the nearest integer. If the fractional bits equal 0.5, rounding is towards the nearest even integer.
  3. Convert from signed to unsigned. If any negative numbers exist in the results and the output type is unsigned, you can convert to unsigned through these methods:
    • Saturate to the minimum output value (constraining to range).
    • Replace negative numbers with their absolute positive value.
  4. Constrain to range. If any of the results are beyond a specific range, the IP automatically adds logic to saturate the results to the minimum and maximum output values. The specific range is the specified range of the output guard bands, or if unspecified, the minimum and maximum values allowed by the output bits per pixel.