The Crop function extracts the region of interest (ROI) from the
input image.
P(X,Y) ≤ P(xi, yi) ≤ P(X’,Y’)
- P(X,Y) - Top left corner of ROI
- P(X’,Y’) - Bottom Right of ROI
API Syntax
template<int SRC_T, int ROWS, int COLS,int ARCH_TYPE=0,int NPC=1, int XF_CV_DEPTH_IN, int XF_CV_DEPTH_OUT>
void crop(xf::cv::Mat<SRC_T, ROWS, COLS, NPC, XF_CV_DEPTH_IN> & _src_mat,xf::cv::Mat<SRC_T, ROWS, COLS, NPC, XF_CV_DEPTH_OUT> &_dst_mat,xf::cv::Rect_<unsigned int> &roi)
Parameter Descriptions
The following table describes the template and the function parameters.
| Parameter | Description |
|---|---|
| SRC_T | Input pixel type. Only 8-bit, unsigned, 1 and 4 channels are supported (XF_8UC1 and XF_8UC4). |
| ROWS | Maximum height of input and output image. |
| COLS | Maximum width of input and output image. Must be multiple of 8 for 8-pixel operation. |
| ARCH_TYPE | Architecture type. 0 resolves to stream implementation and 1 resolves to memory mapped implementation. |
| NPC | Number of pixels to be processed per cycle. NPC should be power of 2. |
| XFCVDEPTH_IN | Depth of input image |
| XFCVDEPTH_OUT | Depth of output image |
| _src_mat | Input image |
| _dst_mat | Output ROI image |
| roi | ROI is a xf::cv::Rect object that consists of the
top left corner of the rectangle along with the
height and width of the rectangle. |
Resource Utilization
The following table summarizes the resource utilization of crop function in normal mode (NPC=1) for 3 ROIs (480x640, 100x200, 300x300) as generated in the Vivado HLS 2019.1 tool for the Xilinx xczu9eg-ffvb1156-2-i-es2 FPGA.
| Name | Resource Utilization | |
|---|---|---|
| 1 pixel per clock operation | 8 pixel per clock operation | |
| 300 MHz | 150 MHz | |
| BRAM_18K | 6 | 8 |
| DSP48E | 10 | 10 |
| FF | 17482 | 16995 |
| LUT | 16831 | 15305 |
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 for 3 ROIs (480x640, 100x200, 300x300).
| Operating Mode | Latency Estimate |
|---|---|
| Max Latency (ms) | |
| 1 pixel operation (300 MHz) | 1.7 |
| 8 pixel operation (150 MHz) | 0.6 |