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 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. 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. The dimension
values of roi must be multiple of NPC |
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 |