Technical word for a screen phenomenon

I hope I have the right board for this question.

I want to know if there is a proper word/term to describe what happens on large hi-definition screens that make a whole image devolve into a series of squares.

For example: The natural curve of a person's face is seen in squares that makes the outline appear in small, linear units.

In newspaper images, I believe that the series of "dots," is referred to as the matrix,, but I don't know if that translates to a broadcast/aired picture.

Thanks