machinevisiontoolbox.Image.npq

Image.npq(p, q)

Normalized central image moments

Parameters:

• p (int) – u exponent

• q (int) – v exponent

Returns:

moment

Type:

scalar

Computes the pq’th normalized central moment of the image:

$$\nu (I)=\frac{{\mu }_{pq}(I)}{m_{00}(I)}=\frac{1}{m_{00}(I)}\sum _{uv}{I}_{uv}(u-u_0{)}^p(v-v_0{)}^q$$

where $u_0=m_{10}(I)/m_{00}(I)$ and $v_0=m_{01}(I)/m_{00}(I)$.

Example:

>>> from machinevisiontoolbox import Image
>>> img = Image.Read('shark1.png')
>>> img.npq(2, 2)
1.1596991128539824e-07

Note:

• The normalized central moments are invariant to translation and scale.

• Supports single channel images only.

References:

• Robotics, Vision & Control for Python, Section 12.1.3.4, P. Corke, Springer 2023.

Seealso:

sum mpq upq