Video and Image Processing Suite User Guide

ID 683416
Date 2/12/2021
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8.1. 2D FIR Filter Processing

The 2D FIR II IP core calculates the output pixel values in 3 stages.
  1. Kernel creation

    An N×M array of input pixels is created around the input pixel at the same position in the input image as the position of the output pixel in the output image. This center pixel has (N-1)/2 pixels to its left and N/2 pixels to its right in the array, and (M-1)/2 lines above it and M/2 lines below it.

    When the pixels to the left, right, above, or below the center pixel in the kernel extend beyond the edges of the image, then the filter uses either replication of the edge pixel or full data mirroring, according to the value of a compile time parameter.

  2. Convolution

    Each pixel in the N×M input array is multiplied by the corresponding coefficient in the N×M coefficient array and the results are summed to produce the filtered value.

    The 2D FIR Filter II IP core retains full precision throughout the calculation of each filtered value, with all rounding and saturation to the required output precision applied as a final stage.

  3. Rounding and saturation.

    The resulting full precision filtered value as rounded and saturated according the output precision specification