The absdiff
function finds the pixel wise absolute difference
between two input images and returns an output image. The input and the
output images must be the XF_8UC1 type.
Where,
- Iout(x, y) is the intensity of output image at (x,y) position.
- Iin1(x, y) is the intensity of first input image at (x,y) position.
- Iin2(x, y) is the intensity of second input image at (x,y) position.
API Syntax
template<int SRC_T, int ROWS, int COLS, int NPC=1, int XFCVDEPTH_IN_1 = _XFCVDEPTH_DEFAULT, int XFCVDEPTH_IN_2 = _XFCVDEPTH_DEFAULT, int XFCVDEPTH_OUT_1 = _XFCVDEPTH_DEFAULT>
void absdiff(
xf::cv::Mat< SRC_T, ROWS, COLS, NPC, XFCVDEPTH_IN_1>& src1,
xf::cv::Mat< SRC_T, ROWS, COLS, NPC, XFCVDEPTH_IN_2>& src2,
xf::cv::Mat< SRC_T, ROWS, COLS, NPC, XFCVDEPTH_OUT_1>& dst )
Parameter Descriptions
The following table describes the template and the function parameters.
Parameter | Description |
---|---|
SRC_T | Input and Output 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. |
NPC | Number of pixels to be processed per cycle; possible options are XF_NPPC1 and XF_NPPC8 for 1 pixel and 8 pixel operations respectively. |
XFCVDEPTH_IN_1 | Depth of the input image |
XFCVDEPTH_IN_2 | Depth of the input image |
XFCVDEPTH_OUT_1 | Depth of the output image |
src1 | Input image |
src2 | Input image |
dst | Output image |
Resource Utilization
The following table summarizes the resource utilization in different configurations, generated using Vivado HLS 2019.1 tool for the Xczu9eg-ffvb1156-1-i-es1 FPGA, to process a grayscale HD (1080x1920) image.
Operating Mode | Operating Frequency (MHz) | Utilization Estimate | ||||
---|---|---|---|---|---|---|
BRAM_18K | DSP_48Es | FF | LUT | CLB | ||
1 Pixel | 300 | 0 | 0 | 62 | 67 | 17 |
8 Pixel | 150 | 0 | 0 | 67 | 234 | 39 |
Performance Estimate
The following table summarizes the performance in different configurations, as generated using Vivado HLS 2019.1 tool for the Xczu9eg-ffvb1156-1-i-es1, to process a grayscale HD (1080x1920) image.
Operating Mode | Latency Estimate |
---|---|
Max Latency (ms) | |
1 pixel operation (300 MHz) | 6.9 |
8 pixel operation (150 MHz) | 1.69 |
Deviation from OpenCV
There is no deviation from OpenCV, except that the absdiff
function
supports 8-bit pixels.