Gradient Magnitude

The xFmagnitude function computes the magnitude for the 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 L1NORM normalization, the magnitude computed image is the pixel-wise added image of absolute of x-gradient and y-gradient, as shown below:.

For L2NORM normalization, the magnitude computed image is as follows:

API Syntax

template< int NORM_TYPE ,int SRC_T,int DST_T, int ROWS, int COLS,int NPC=1>
void xFmagnitude(xF::Mat<SRC_T, ROWS, COLS, NPC> & _src_matx,xF::Mat<DST_T, ROWS, COLS, NPC> & _src_maty,xF::Mat<DST_T, ROWS, COLS, NPC> & _dst_mat)

Parameter Descriptions

The following table describes the template and the function parameters.

Table 1. xFmagnitude Function Parameter Descriptions
Parameter	Description
NORM_TYPE	Normalization type can be either L1 or L2 norm. Values are XF_L1NORM or XF_L2NORM
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 (must be a multiple of 8)
COLS	Maximum width of input and output image (must be a multiple of 8)
NPC	Number of pixels to be processed per cycle; possible values are XF_NPPC1 and XF_NPPC8 for 1 pixel and 8 pixel operations respectively.
_src_matx	First input, x-gradient image.
_src_maty	Second input, y-gradient image.
_dst_mat	Output, magnitude computed image.

Resource Utilization

The following table summarizes the resource utilization of the kernel in different configurations, generated using Vivado HLS 2017.1 tool for the Xilinx Xczu9eg-ffvb1156-1-i-es1 FPGA, to process a grayscale HD (1080x1920) image and for L2 normalization.

Table 2. xFmagnitude Function Resource Utilization Summary
Name	Resource Utilization
	1 pixel	8 pixel
	300 MHz	150 MHz
BRAM_18K	0	0
DSP48E	2	16
FF	707	2002
LUT	774	3666
CLB	172	737

Performance Estimate

The following table summarizes the performance of the kernel in different configurations, as generated using Vivado HLS 2017.1 tool for the Xilinx Xczu9eg-ffvb1156-1-i-es1, to process a grayscale HD (1080x1920) image and for L2 normalization.

Table 3. xFmagnitude Function Performance Estimate Summary
Operating Mode	Operating Frequency (MHz)	Latency Estimate
Operating Mode	Operating Frequency (MHz)	Max (ms)
1 pixel	300	7.2
8 pixel	150	1.7