What is the difference between a weighted mean filter and an alternative mean filter in low pass filtering?

For an assignment, I've been asked to implement both of these filters and apply them to an image with salt and pepper noise.

Based on the lecture notes, I'm having trouble understanding the difference between a weighted mean filter and an alternative

mean filter. I would appreciate If someone could clarify.

Answer 1

[KALYAN ACHARJYA]

As per my undestanding, in weigthed mean the mask coefficients are not "1"

[KALYAN ACHARJYA]

Use the mask coefficients than mean of the 3x3 image segment.