Scharr Filter

The xFScharr function computes the gradients of input image in both x and y direction by convolving the kernel with input image being processed.

For Kernel size 3x3:

GradientX:
GradientY:

API Syntax

template<int BORDER_TYPE, int SRC_T,int DST_T, int ROWS, int COLS,int NPC=1>
void xFScharr(xF::Mat<SRC_T, ROWS, COLS, NPC> & _src_mat,xF::Mat<DST_T, ROWS, COLS, NPC> & _dst_matx,xF::Mat<DST_T, ROWS, COLS, NPC> & _dst_maty)

Parameter Descriptions

The following table describes the template and the function parameters.

Table 1. xFScharr Function Parameter Descriptions
Parameter	Description
BORDER_TYPE	Border Type supported is XF_BORDER_CONSTANT
SRC_T	Input pixel type. Only 8-bit, unsigned, 1 channel is supported (XF_8UC1)
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 options are XF_NPPC1 and XF_NPPC8 for 1 pixel and 8 pixel operations respectively.
_src_mat	Input image
_dst_matx	X gradient output image.
_dst_maty	Y gradient output 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.

Table 2. xFScharr Function Resource Utilization Summary
Name	Resource Utilization
	1 pixel	8 pixel
	300 MHz	150MHz
BRAM_18K	3	6
DSP48E	0	0
FF	728	1434
LUT	812	2481
CLB	171	461

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.

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