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.
Programming Point Processing Operations
When implementing one of the point processing operations in software the follow-
ing is done.
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