A histogram is created for each tile using which histogram equalization is performed.
API Syntax
CLAHEImpl Class API:
template <int IN_TYPE, int HEIGHT, int WIDTH, int NPC, int CLIPLIMIT, int TILES_Y_MAX, int TILES_X_MAX, int TILES_Y_MIN = 4, int TILES_X_MIN = 4, int XFCVDEPTH_IN_1 = _XFCVDEPTH_DEFAULT, int XFCVDEPTH_OUT_1 = _XFCVDEPTH_DEFAULT>
class CLAHEImpl {}
Processing member function:
xf::cv::clahe::CLAHEImpl<IN_TYPE, HEIGHT, WIDTH, NPC, CLIPLIMIT, TILES_Y_MAX, TILES_X_MAX, TILES_Y_MIN, TILES_X_MIN, XF_CV_DEPTH_IN_1, XF_CV_DEPTH_OUT_1>::process(imgOutput, imgInput, _lutw, _lutr, _clipCounter, height, width, clip, tilesY, tilesX)
Parameter Descriptions
The following table describes the template and the function parameters.
| Paramete r | Description |
|---|---|
| IN_TYPE | Input pixel type. The current supported pixel value is XF_8UC1. |
| HEIGHT | Maximum height of input and output image. |
| WIDTH | Maximum width of input and output image. |
| NPC | Number of pixels to be processed per cycle; possible options are XF_NPPC1 for 1 pixel operation. |
| CLIPLIMIT | Number of pixels to be processed per cycle; possible options are XF_NPPC1 for 1 pixel operation. |
| TILES_Y_MAX | Max range of number of tiles created vertically |
| TILES_X_MAX | Min range of number of tiles created horizontally |
| TILES_Y_MIN | Min range of number of tiles created vertically |
| TILES_X_MIN | Max range of number of tiles created horizontally |
| XF_CV_DEPTH_IN_1 | Depth of input image |
| XF_CV_DEPTH_OUT_1 | Depth of output image |
Resource Utilization
The following table summarizes the resource utilization of the clahe function, generated using vitis HLS 2022.1 tool for the xcu200-fsgd2104-2-e FPGA.
| Operating Mode | Operating Frequency (MHz) | Utilization Estimate | ||||
|---|---|---|---|---|---|---|
| BRAM_18K | DSP_48Es | FF | LUT | CLB | ||
| 1 Pixel | 300 | 0.5 | 77 | 376 | 15468 | 2969 |
Performance Estimate
The following table summarizes the performance in different configurations, as generated using vitis HLS 2022.1 tool for the xcu200-fsgd2104-2-e.
| Operating Mode | Latency Estimate |
|---|---|
| Max Latency (ms) | |
| 1 pixel operation (300 MHz) | 1.8592 |