[Feature]: Implement a Vignette filter

[harshsankhla18]

So, what is it about?

Implement a vignette filter algorithm function using standard logic, Darken corners gradually for cinematic look.

Additionally, add command-line tags, such as 'g' for grayscale and 's' for sepia, for function selection. Add Its algorithm in readme.md.

Code of Conduct

• I agree to follow this project's Code of Conduct

[Satvik-Singh192]

@harshsankhla18 please assign this issue to me

[harshsankhla18]

Okay try to do it by 22 oct , otherwise i may assign it to someone else too.
edit: I am assigning it to @saumya1317 too

[saumya1317]

assign this to me pls

[harshsankhla18]

Hey @saumya1317 , You pls first register for OpCode through discord otherwise i may not prioritize your PR as it will not be beneficial for you too.

[saumya1317]

also i have registered through dicord as well

[saumya1317]

@harshsankhla18 do check my pull request