sobel filter implementation using Vision HDL Toolbox

sobel filter implementation using Vision HDL Toolbox, to compare with Xilinx XAPP890

this is the implementation of sobel filter using Vision HDL toolbox, in order to compare with the Xilinx HLS XAPP890.
Some points need notice:
1. The filter can be easily replaced with image filter module from Vision HDL Toolbox.
2. Some pixel of the output image is different from that in Xilinx XAPP, the reason is due to the type conversion