Matrices Question

Matrices are widely used in image processing, where images are taken and manipulated in some way. To simplify this, consider a grayscale image (an image without color, but with varying hues of gray). Each pixel in the image has an assigned value, from 0 (completely black) to 255 (completely white). Usually, an image would be comprised of thousands or more pixels, but again, for simplification, consider a 3-by-3 matrix. Let the image be represented by the matrix A, as follows.

`A = [[124, 127, 129], [118, 120, 124], [115, 119, 121]]`

Which of the following operations would "invert" the grayscale image- that is, give the opposite intensity of each pixel? For example, if the original image has a pixel that was almost white, 4, the same pixel in the resulting image would be 251, almost black.

1. `A^{-1}` (inverse of matrix A)
2. `A^T` (transpose of matrix A)
3. `255*[[1,1,1],[1,1,1],[1,1,1]] - A`
4. `A - 255*[[1,1,1],[1,1,1],[1,1,1]]`