[Feature]: Implement Sepia Function in helpers.c

[harshsankhla18]

So, what is it about?

Convert each pixel into a sepia-toned pixel using the standard formula.

Code of Conduct

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

[Tarun2605]

Can this issue be assigned to me? (I have studied image processing for 2 semesters back to back 💯 )

[saumya1317]

assign this to me

[ekanshgupta2046]

I will implement a sepia image filter that converts each pixel’s RGB values using the standard sepia formula and clamps the results between 0 and 255 while keeping the alpha channel unchanged. This will give the image a warm, vintage tone.

Please assign me this issue.