Absolute Difference - 2023.2 English

Vitis Libraries

Release Date
2023-12-20
Version
2023.2 English

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.


image0

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.

Table 267 Table absdiff Parameter Description
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.

Table 268 Table absdiff Function Resource Utilization Summary
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.

Table 269 Table absdiff Function Performance Estimate Summary
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.