ansmit=
PD (x,y)
red
3 and
is
)sod
secund
nortan
lis-
5
trens-
3
1e
es in
ical
lly the
, (20).
ront
. Hou-
gurat-
dot
ed,
d
con-
sition
of L5 , P, end P5, . This flexibility.is of considerable
utility in spatiál filtering applications and when con-
sidering the analysis of the trensform,since the adjust-
ment of its scele results in an easier analysis possibi-
litv.
t x4 y ) can be expressed in function of tfe opticel dene
sity Db iy4] of the film as
-in(y)
t (xy) = 10° (11)
Following from this equation and combining equations 6 and 7, it
results:
ALL
thoy) = & [1-846] * (12)
where
„4171
2
A
i"
o [CT 1,6) (13)
and
Ag Lem (14)
If a sinuscidal amplitude grating is defined by t4 (x 31) 2 > .
(1 « eos ux), then t. is anelogous to dc bies ters end 4 ie
analogcus to nodulation (contrest) w (15). Hence a Film input
with low bias. level and high modulation is desirable.
In the following we will briefly consider the relationship
between the hight spectrum and the slope spectrum. The power
spectrum E(K) of the surface waves of wave number k is defined
by
E(R,t) = ON mm: ear (15)
where n (X,t) is the elevation of the sea surface at location X
end time t; r is the distance betusen the tuo reference points
and the bar indicates the average about X (12). Since optical
density of vertical wave photographs is proportional to the
surface slope |Vn|, it may be expressed as:
F(K,t) = C J EZTGYTEZTEST el ge (16)
where C is a constant. Here the dependence uith t is dropped.