added dynamic brightness feature

[vanshxbansal]

-if image is dull or dark then its brightness will be increased so that no wrong scan take place -in my case the default brightness I was taking is 200 and above these images where getting scan correctly below problem was there

• also image overall brightness is not increased first image is divided in four quadrant then brightness of each quadrant is checked with 200 and if lower then increased to near 200 ,this will also help in those image where image is taken using mobiles with flash light on [uneven brightness on image]

[palash018]

Good work! However, there are cases where a fixed scaler value of 200 may not be sufficient. I would like to suggest some improvements : -

• It would be better if the value was dynamic, with scope for a slider GUI that can change the value.
• A slider would allow users to see the "before and after" effects more easily.
• In the case of a container, the value can be passed as arguments or configured instead of using a GUI.
• Consider incorporating multiple brightening functions, such as gamma correction, for better results.

[Udayraj123]

Closing due to solution not being outdated now and not generalised enough. Closing in favour of the AutoContrast preprocessor added in v2 that serves the purpose well.

p.s. Thank you the efforts! Feel free to reply/open a new PR if I missed anything.