idrisr/art_of_R_prog — pull request #1 by tkumark (2014-04-17 17:44:38+00:00)
Title: Update author_letter.R

tried using
newimg@grey[rows, cols] <- randomnoise
newimg@grey <- (1-q) * img@grey + q * randomnoise
but got "non-conformable arrays" error
newimg@grey[rows,cols] <- (1-q) * img@grey[rows,cols] + q * randomnoise
is required