2D Median Filter Design Example
This design example shows how to perform a two-dimensional median filtering operation on video stream data in DSP Builder. The 2D Median Filter MegaCore® function is widely used to remove salt and pepper noise in the input video. In this example, the 2D Median Filter MegaCore function replaces the central value of a 3-by-3 neighborhood with its median value. At the boundary of the video frame, the filter pads the input matrix with 0's.
The model consists of an image stream source block, a 2D median filtering block, and an image stream sink block. The image stream source block reads the input binary file and feeds the data stream to the 2D median filtering block. The image stream sink block writes the filtered data stream to an output binary file. The package also includes the utility to convert an avi video file format to and from a binary file format.
Download the files used in this example:
Files in the zip download include:
- example_2dmedian_<version number>.mdl - DSP Builder design file
- median_filter_2d.vhd - Wrapper file to generate the Altera® 2D Median Filter intellectual property (IP) MegaCore function
- avi-is-avi.exe - DOS executable to convert an avi file to and from a binary file
Figure 1 shows the top-level diagram of the 2D Median Filter design example in DSP Builder.
Figure 1. 2D Median Filter Design Example
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Table 1 lists the ports and gives a description for each.
| Table 1. 2D Median Port Listing |
| Port Name |
Type |
Description |
din[7:0] |
Input |
Data input bus |
din_valid |
Input |
Data valid signal that indicates the validity of the input data signals |
dout_ready |
Input |
Data output ready signal |
reset |
Input |
Reset signal |
din_ready |
Output |
Data input ready signal |
dout[7:0] |
Output |
Data output bus |
dout_valid |
Output |
Data valid signal that indicates the validity of the output data signals |
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