# Wikibooksβ

## DescriptionEdit

This component subtract the background image from the input image. If the camera is fixed, only the objects added to the scene remain after this subtraction. However, lighting condition variations or the camera noise can also produce a difference between the two images. Subtracting average intensity of the two images makes the system less sensible to lighting conditions.

Method doesn't need a background image as it approximate the background from the prior frames. However the moving objects tend to let a trail behind them.

Most of the time, a threshold is applied after this method, to separate the background from the tracked objects.

A color image.

A color image.

## ParametersEdit

### Correct meanEdit

Specify whether to correct the average intensity value of the input image with the average intensity value of the background image. This option makes the tracking less sensible to lighting conditions variations.

### Update proportionEdit

The background image is continuously update with the update image following the following equation:

${\displaystyle backgroundImage_{t}=backgroundImage_{t-1}\cdot (1-updateProportion)+inputImage_{t}\cdot updateProportion}$

Therefore, increasing the proportion makes the update of the background more reactive, but will remove object moving slowly.