Mode filter is a non-linear digital filter which improves noise reduction. This implements filter operation with given size of N by computing mode for all the pixels in an NxN window.
API Syntax
template <int FILTER_SIZE, int BORDER_TYPE, int TYPE, int ROWS, int COLS, int NPC = 1, int XFCVDEPTH_IN = _XFCVDEPTH_DEFAULT, int XFCVDEPTH_OUT = _XFCVDEPTH_DEFAULT>
void modefilter(xf::cv::Mat<TYPE, ROWS, COLS, NPC, XFCVDEPTH_IN>& _src, xf::cv::Mat<TYPE, ROWS, COLS, NPC, XFCVDEPTH_OUT>& _dst)
Parameter Descriptions
The following table describes the template and the function parameters.
| 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 | Input and Output pixel type. Only 8-bit, unsigned, 1 or 3 channels are supported (XF_8UC1 and XF_8UC3) |
| ROWS | Number of rows in the image being processed. |
| COLS | Number of columns in the image being processed. Must be a multiple of 8, for 8-pixel operation. |
| 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 |
| XFCVDEPTH_IN | Depth of the input image. |
| XFCVDEPTH_OUT | Depth of the output image. |
| _src | Input image. |
| _dst | Output image. |
Resource Utilization
The following table summarizes the resource utilization of the Mode filter function for XF_NPPC1 configurations, generated using Vitis HLS 2020.2 version tool.
| Operating Mode | FILTER_SIZE | Operating Frequency (MHz) | Utilization Estimate | |||
|---|---|---|---|---|---|---|
| LUTs | FFs | DSPs | BRAMs | |||
| 1 pixel | 3 | 300 | 628 | 900 | 0 | 3 |
| 1 pixel | 5 | 300 | 2579 | 4070 | 0 | 5 |
| 1 pixel | 7 | 300 | 7852 | 14065 | 0 | 7 |
Performance Estimate
The following table summarizes performance estimates of Mode filter function on Vitis HLS 2020.2 version tool.
| Operating Mode | FILTER_SIZE | Operating Frequency (MHz) | Input Image Size | Latency Estimate Max (ms) |
|---|---|---|---|---|
| 1 pixel | 3 | 300 | 1920x1080 | 6.99 |
| 1 pixel | 5 | 300 | 1920x1080 | 7.00 |
| 1 pixel | 7 | 300 | 1920x1080 | 7.15 |