Median Blur Filter

The function xFMedianBlur performs a median filter operation on the input image. The median filter acts as a non-linear digital filter which improves noise reduction. A filter size of N would output the median value of the NxN neighborhood pixel values, for each pixel.

API Syntax

template void xFMedianBlur (xF::Mat & _src, xF::Mat & _dst)

Parameter Descriptions

The following table describes the template and the function parameters.

Table 1.xFMedianBlur Function Parameter Descriptions
Parameter Description
FILTER_SIZE Window size of the hardware filter for which the hardware kernel will be built. This can be any odd positive integer greater than 1.
BORDER_TYPE The way in which borders will be processed in the hardware kernel. Currently, only XF_BORDER_REPLICATE is supported.
TYPE Type of input pixel. XF_8UC1 is supported.
ROWS Number of rows in the image being processed.
COLS Number of columns in the image being processed.
NPC Number of pixels to be processed in parallel. Options are XF_NPPC1 (for 1 pixel processing per clock), XF_NPPC8 (for 8 pixel processing per clock
_src Input image.
_dst Output image.

Resource Utilization

The following table summarizes the resource utilization of the xFMedianBlur function for XF_NPPC1 and XF_NPPC8 configurations, generated usingVivado HLS 2017.1version tool for the Xilinx Xc7z020clg484-1 FPGA.

Table 2.xFMedianBlur Function Resource Utilization Summary
Operating Mode FILTER_SIZE

Operating Frequency

(MHz)

 Utilization Estimate
LUTs FFs DSPs BRAMs
1 pixel 3 300 1197 771 0 3
8 pixel 3 150 6559 1595 0 6
1 pixel 5 300 5860 1886 0 5

Performance Estimate

The following table summarizes performance estimates of xFMedianBlur function onVivado HLS 2017.1version tool for the Xilinx xczu9eg-ffvb1156-1-i-es1 FPGA.

Table 3.xFMedianBlur Function Performance Estimate Summary
Operating Mode FILTER_SIZE

Operating Frequency

(MHz)

 Input Image Size Latency Estimate
Max (ms)
1 pixel 3 300 1920x1080 6.99
8 pixel 3 150 1920x1080 1.75
1 pixel 5 300 1920x1080 7.00