edge_detection.py

treshold = 100

matrix = []

with open('image-brightness-values.csv') as csv_file:
    for line in csv_file.readlines():
        matrix.append(map(int, line.split(',')))

def process_line(line):
    pairs = zip(line, line[1:])
    sub = lambda (x, y): abs(x-y)
    diffs = map(sub, pairs)

    return [
        '-' if d < treshold else '|'
        for d in diffs
    ]

edges = map(process_line, matrix)

for l in edges:
    print ' '.join(l)