Distance Transform Feature Matcher - 2023.2 English

The distance transform is an operator normally only applied to binary images, where in this case the image must be coded as zero and non-zero pixels as a grayscale image. The result of the transform is a graylevel image that looks similar to the input image, except that the graylevel intensities of points inside foreground regions are changed to show the distance to the closest boundary from each point.

This Xilinx implementation applies 3x3 mask, of distance type DIST_L2 (Euclidean distance), with horizontal/vertical shift cost, a = 0.955, and diagonal shift cost b = 1.3693.

Computing the distance takes two passes, forward and backward. During the forward pass, forward mask is applied, and while the backward pass the backward mask is applied over the forward pass data. In this implementation, it is required to pass a cache memory for the kernel to interact (write while forward pass, read while backward pass). The cache memory must be of image dimensions and of type ap_uint<32>.

API Syntax

template <int IN_PTR, int FW_PTR, int ROWS, int COLS, int USE_URAM>
void distanceTransform(ap_uint<IN_PTR>* _src,
                       float* _dst, ap_uint<FW_PTR>* _fw_pass,
                       int rows, int cols)

Parameter Descriptions

The following table describes template paramters and arguments of the function.

Resource Utilization

The following table summarizes the resource utilization of the kernel in different configurations, generated using Vitis 2020.2 tool, to process a 4K image.

Performance Estimate

The following table summarizes a performance estimate of the kernel in different configurations, as generated using Vitis 2020.2 tool, to process a 4K image.