The InRange function checks if pixels in the image src lie between the given boundaries. dst(x,y) is set to 255, if src(x,y) is within the specified thresholds and otherwise 0.
Dst(I)= lowerb ≤ src(I) ≤ upperb
Where (x,y) is the spatial coordinate of the pixel.
API Syntax
template<int SRC_T, int ROWS, int COLS,int NPC=1, int XFCVDEPTH_IN = _XFCVDEPTH_DEFAULT, int XFCVDEPTH_OUT = _XFCVDEPTH_DEFAULT>
void inRange(xf::cv::Mat<SRC_T, ROWS, COLS, NPC, XFCVDEPTH_IN> & src,unsigned char lower_thresh,unsigned char upper_thresh,xf::cv::Mat<SRC_T, ROWS, COLS, NPC, XFCVDEPTH_OUT> & dst)
Parameter Descriptions
The following table describes the template and the function parameters.
| Parameter | Description |
|---|---|
| SRC_T | Input Pixel Type. 8-bit, unsigned, 1 and 3 channels are supported (XF_8UC1 and XF_8UC3). |
| 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 | Depth of the input image. |
| XFCVDEPTH_OUT | Depth of the output image. |
| src | Input image |
| dst | Output image |
| lower_thresh | Lower threshold value |
| upper_thresh | Upper threshold value |
Resource Utilization
The following table summarizes the resource utilization of the InRange 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 | 86 | 154 |
| LUT | 60 | 148 |
| CLB | 15 | 37 |
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 |