The Max function calculates the per-element maximum of two corresponding images src1, src2 and stores the result in dst.
dst(x,y)=max( src1(x,y) ,src2(x,y) )
API Syntax
template< int SRC_T , int ROWS, int COLS, int NPC=1, int XFCVDEPTH_IN_1 = _XFCVDEPTH_DEFAULT, int XFCVDEPTH_IN_2 = _XFCVDEPTH_DEFAULT, int XFCVDEPTH_OUT_1 = _XFCVDEPTH_DEFAULT>
void max(xf::cv::Mat<SRC_T, ROWS, COLS, NPC, XFCVDEPTH_IN_1> & _src1, xf::cv::Mat<SRC_T, ROWS, COLS, NPC, XFCVDEPTH_IN_2> & _src2, xf::cv::Mat<SRC_T, ROWS, COLS, NPC, XFCVDEPTH_OUT_1> & _dst)
Parameter Descriptions
The following table describes the template and the function parameters.
| Parameter | Description |
|---|---|
| SRC_T | Input Pixel Type. 8-bit, unsigned, 1 channel is supported (XF_8UC1). |
| ROWS | Maximum height of input and output image. |
| COLS | Maximum width of input and output image. In case of N-pixel parallelism, width should be multiple of N. |
| NPC | Number of pixels to be processed per cycle; possible options are XF_NPPC1 and XF_NPPC8 for 1 pixel and 8 pixel operations respectively. |
| XFCVDEPTH_IN_1 | Depth of the input image. |
| XFCVDEPTH_IN_2 | Depth of the input image. |
| XFCVDEPTH_OUT_1 | Depth of the output image. |
| _src1 | First input image |
| _src2 | Second input image |
| _dst | Output image |
Resource Utilization
The following table summarizes the resource utilization of the Max function in Resource optimized (8 pixel) mode and normal mode as generated using Vivado HLS 2019.1 version tool for the Xczu9eg-ffvb1156-1-i-es1 FPGA.
| Name | Resource Utilization | |
|---|---|---|
| 1 pixel per clock operation | 8 pixel per clock operation | |
| 300 MHz | 150 MHz | |
| BRAM_18K | 0 | 0 |
| DSP48E | 0 | 0 |
| FF | 103 | 153 |
| LUT | 44 | 102 |
| CLB | 21 | 38 |
Performance Estimate
The following table summarizes a performance estimate of the kernel in different configurations, generated using Vivado HLS 2019.1 tool for Xczu9eg-ffvb1156-1-i-es1 FPGA to process a grayscale HD (1080x1920) image.
| Operating Mode | Latency Estimate |
|---|---|
| Max Latency (ms) | |
| 1 pixel operation (300 MHz) | 6.9 |
| 8 pixel operation (150 MHz) | 1.7 |