Image Processing Reference
In-Depth Information
Fig. 4.26
Input image and
inverted image
Fig. 4.27
Examples of alpha blending, with different alpha values
where
α
∈[
0
,
1
]
and
α
is the Greek letter “alpha”, hence the name alpha blending.
If
α
0
.
5 then the two images are mixed equally and Eq.
4.18
has the same effect
as Eq.
4.16
.InFig.
4.27
, a mixing of two images is shown for different values of
α
.
In Eq.
4.18
,
α
is the same for every pixel, but it can actually be different from
pixel to pixel. This means that we have an entire image (with the same size as
f
1
(x, y), f
2
(x, y)
and
g(x,y)
) where we have
α
-values instead of pixels:
α(x,y)
.
Such an “
α
-image” is often referred to as an
alpha-channel
. This can for example
be used to define the transparency of an object.
=
4.7
Programming Point Processing Operations
When implementing one of the point processing operations in software the follow-
ing is done.
