Vignetting/Lensshading refers to the fall-off pixel intensity from the centre towards the edges of the image. In this algorithm, vignette is corrected by considering the distance between the centre pixel and actual image pixel position. This distance is used to calculate intensity gain per pixel per channel which is used for the correction.
API Syntax
template <int SRC_T, int DST_T, int ROWS, int COLS, int NPC = 1, int XFCVDEPTH_IN = _XFCVDEPTH_DEFAULT, int XFCVDEPTH_OUT = _XFCVDEPTH_DEFAULT>
void Lscdistancebased(xf::cv::Mat<SRC_T, ROWS, COLS, NPC, XFCVDEPTH_IN>& src, xf::cv::Mat<DST_T, ROWS, COLS, NPC, XFCVDEPTH_OUT>& dst) {
Parameter Descriptions
The following table describes template parameters and arguments to the function.
| Parameter | Description |
|---|---|
| SRC_T | Input pixel type. 8/10/12/16-bit, unsigned, Bayer format is supported (XF_8UC1, XF_10UC1, XF_12UC1, XF_16UC1). |
| DST_T | Output pixel type. 8/10/12/16-bit, unsigned, Bayer format is supported (XF_8UC1, XF_10UC1, XF_12UC1, XF_16UC1). |
| 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, XF_NPPC2 AND so on |
| 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 kernel in different configurations, generated using Vitis HLS 2020.2 tool, to process a FULL HD image.
| Operating Mode | Operating Frequency (MHz) | Utilization Estimate | ||||
|---|---|---|---|---|---|---|
| BRAM_18K | DSP_48Es | FF | LUT | CLB | ||
| 1 pixel-8U | 300 | 0 | 20 | 3584 | 2946 | 681 |
| 1 pixel-16U | 300 | 0 | 20 | 3608 | 2978 | 673 |
Performance Estimate
The following table summarizes a performance estimate of the kernel in different configurations, as generated using Vitis HLS 2020.2 tool, to process a FULL HD image.
| Operating Mode | Operating Frequency (MHz) | Latency Estimate Max (ms) |
|---|---|---|
| 1 pixel | 300 | 7 |
| 2 pixel | 300 | 3.6 |