# Find QR keypoints

Finds location of a QR code and returns 13 key points of the code. The points are given in both pixel coordinates and in coordinates relative to the base corner of the QR code. Base corner is the corner which has a finder pattern at the corner and on both sides of the corner. There is only one such corner in a QR code.

Example:

F... F = a corner with a finder pattern
.... B = Base corner (which also has a finder pattern)
B..F

Typically the output of this tool is connected to pointset positioning.

## Inputs

image
Input image.
threshold
Threshold for separating the modules of matrix code from the background.
invert
Invert flag. If the flag is set to true, the tool assumes a black code on white background. This can be changed by setting the invert flag to false.
edgeLength
Length of the edge of the QR code in physical units (e.g. millimeters or inches).

## Outputs

keyPoints
A 13-by-2 matrix of world coordinates of the key points found in the input image.
referencePoints
A 13-by-2 matrix of reference points. The origin of the coordinate system is relative to the base corner of the detected QR code.