There is more to it
this image contains 6 letters, it just needs a higher contrast
a -> 1,4,5
b -> 5,6
c -> 7
d -> 2
e -> 1,6
f -> 2,4
g -> 1
h -> 5,6
i -> 4
j -> 6
k -> 5
l -> 1,2
m -> 2,3,4
n -> 1,4,5
o -> 4,5
p -> 2,3
q -> 1,6
r -> 2
s -> 2,4
t -> 3,6
u -> 3
v -> 2
w -> 5
x -> 1,5
y -> 6
z -> 4,5