Black level leads to the whitening of image in dark region and perceived loss of overall contrast. The Blacklevelcorrection algorithm corrects the black and white levels of the overall image.
API Syntax
template <int SRC_T,int MAX_ROWS,int MAX_COLS,int NPPC = XF_NPPC1,int MUL_VALUE_WIDTH = 16,int FL_POS = 15,int USE_DSP = 1, int XFCVDEPTH_IN = _XFCVDEPTH_DEFAULT, int XFCVDEPTH_OUT = _XFCVDEPTH_DEFAULT>
void blackLevelCorrection(xf::cv::Mat<SRC_T, MAX_ROWS, MAX_COLS, NPPC, XFCVDEPTH_IN>& _Src,
xf::cv::Mat<SRC_T, MAX_ROWS, MAX_COLS, NPPC, XFCVDEPTH_OUT>& _Dst,
XF_CTUNAME(SRC_T, NPPC) black_level,
float mul_value)
Parameter Descriptions
The following table describes the template and the function parameters.
| Parameter | Description |
|---|---|
| MUL_VALUE_WIDTH | Width of multiplication factor. |
| FL_POS | Number of fractional bits in multiplication factor. |
| USE_DSP | Enables usage of DSP for multiplication. |
| SRC_T | Input pixel type. 8/10/12/16-bit unsigned 1 channel are supported (XF_8UC1, XF_10UC1, XF_12UC1, XF_16UC1). |
| MAX_ROWS | Maximum height of input and output image. |
| MAX_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 input image |
| XFCVDEPTH_OUT | Depth of output image |
| _Src | Input image |
| _Dst | Output image |
| black_level | Black level value |
| mul_value | Multiplication factor for blacklevel correction; which is computed as maxlevel/(maxlevel-blacklevel) |
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 | 0 | 279 | 271 | 70 |
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 |