Errata for An Interdisciplinary Introduction to Image Processing: Pixels, Numbers, and Programs

p.222, the boxed formula in the lower half of the page should be:

p.263, line 4 of the boxed program example: friend should be who.
p.264, line 13 of the bottom example: the string should be 'abcde'.
p.284, change the first line (line 20 of the code) to:
      if elt==0: dx+=1; continue # if elt is 0, don't even

p.296, 3rd line on page (line 13 of the top example): the string should be 'abcde'.
p.301, line 5 of the boxed example should be
 >>> lst.append('d')

p.370, in the formula for Gy, the second line should be
- I(x-1,y+1) - 2I(x,y+1) - I(x+1,y+1)