Gradient Phase - 2023.1 English

The phase function computes the polar angles of two images. The input images are x-gradient and y-gradient images of type 16S. The output image is of same type as the input image.

For radians:

For degrees:

API Syntax

template<int RET_TYPE ,int SRC_T,int DST_T, int ROWS, int COLS,int NPC=1, int XFCVDEPTH_IN_X = _XFCVDEPTH_DEFAULT, int XFCVDEPTH_IN_Y = _XFCVDEPTH_DEFAULT, int XFCVDEPTH_OUT = _XFCVDEPTH_DEFAULT>
void phase(xf::cv::Mat<SRC_T, ROWS, COLS, NPC, XFCVDEPTH_IN_X> & _src_matx,xf::cv::Mat<DST_T, ROWS, COLS, NPC, XFCVDEPTH_IN_Y> & _src_maty,xf::cv::Mat<DST_T, ROWS, COLS, NPC, XFCVDEPTH_OUT> & _dst_mat)

Parameter Descriptions

The following table describes the template and the function parameters.

Table 527 Table . phase Parameter Description
Parameter	Description
RET_TYPE	Output format can be either in radians or degrees. Options are XF_RADIANS or XF_DEGREES. If the XF_RADIANS option is selected, phase API will return result in Q4.12 format. The output range is (0, 2 pi). If the XF_DEGREES option is selected, xFphaseAPI will return result in Q10.6 degrees and output range is (0, 360).
SRC_T	Input pixel type. Only 16-bit, signed, 1 channel is supported (XF_16SC1).
DST_T	Output pixel type. Only 16-bit, signed, 1 channel is supported (XF_16SC1)
ROWS	Maximum height of input and output image.
COLS	Maximum width of input and output image (must be a 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_X	Depth of the input image.
XFCVDEPTH_IN_Y	Depth of the input image.
XFCVDEPTH_OUT_1	Depth of the output image.
_src_matx	First input, x-gradient image.
_src_maty	Second input, y-gradient image.
_dst_mat	Output, phase computed image.

Resource Utilization

The following table summarizes the resource utilization of the kernel 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 528 Table . phase Function Resource Utilization Summary
Name	Resource Utilization
	1 pixel per clock operation	8 pixel per clock operation
	300 MHz	150 MHz
BRAM_18K	6	24
DSP48E	6	19
FF	873	2396
LUT	753	3895
CLB	187	832

Performance Estimate

The following table summarizes the performance of the kernel 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 529 Table . phase Function Performance Estimate Summary
Operating Mode	Operating Frequency (MHz)	Latency Estimate (ms)
1 pixel	300	7.2
8 pixel	150	1.7

Deviation from OpenCV

In phase implementation, the output is returned in a fixed point format. If XF_RADIANS option is selected, phase API will return result in Q4.12 format. The output range is (0, 2 pi). If XF_DEGREES option is selected, phase API will return result in Q10.6 degrees and output range is (0, 360).