Mastering OpenCV 4 with Python

Shift parameter in drawing functions

Some of the previous functions (the ones with the shift parameter) can work with sub-pixel accuracy in connection with the pixel coordinates. To cope with this, you should pass the coordinates as fixed-point numbers, which are encoded as integers.

A fixed-point number means that there is a specific (fixed) number of digits (bits) reserved for both the integer (on the left of the decimal point) and the fractional parts (on the right of the decimal point).

Therefore, the shift parameter allows you to specify the number of the fractional bits (on the right of the decimal point). In the end, the real point coordinates are calculated as follows:

For example, this piece of code draws two circles with a radius ...