| Image
Processing Articles
Index |
 |
| Basic
Working Mechanism |
| I
mentioned in my previous
article on Image Subtraction
about the basic phenomena
of the nature about
the mixture of colors.
In its most straightforward
implementation, this
operator takes as
input two identically
sized images and produces
as output a third
image of the same
size as the first
two, in which the
intensity of each
pixel is the sum of
the values of the
corresponding pixels
from each of the two
input images. More
sophisticated versions
allow more than two
images to be combined
with a single operation. |
|
| A
common variant of
the operator simply
allows a specified
constant to be added
to every pixel. |
|
| General
Working |
|
| The
subtraction of two
images is performed
straightforwardly
in a single pass.
The output pixel values
are given by: |
|
| Q(x,y)=f(x,y)-
h(x,y) |
| Or
if it is simply desired
to subtract a constant
value C to a single
image then: |
| Q(i,j)=P(i,j)-
C |
|
| Where
to Use Image Subtraction? |
| Image
subtraction is widely
used in the enhancement
of the differences
between images. This
is the basic rule
of Image Processing
that the higher-order
bit planes of an image
carry a significant
amount of visually
relevant detail, while
the lower planes contribute
more to fine (often
imperceptible) detail. |
|
| one
of the most successful
and beneficial uses
of image subtraction
is in the area of
medical imaging called
mask mode radiography.
In this case h(x,
y), the mask, is an
X-ray image of a region
of a patient's body
captured by an intensified
TV camera (instead
of traditional X-ray
film) located opposite
an X-ray source.The
procedure consists
of injecting a contrast
medium into the patient's
bloodstream, taking
a series of images
of the same anatomical
region as h(x, y),
and subtracting this
mask from the series
of incoming images
after injection of
the contrast medium.
The net effect of
subtracting the mask
from each sample in
the incoming stream
of TV images is that
the areas that are
different between
f(x, y) and h(x, y)
appear in the output
image as enhanced
detail. Because images
can be captured at
TV rates, this procedure
in essence gives a
movie showing how
the contrast medium
propagates through
the various arteries
in the area being
observed. |
|
| Guidelines
for Use |
| To
understand the working
of the Image Subtraction,
take the example of
the following images: |
|
 |
 |
|
| the
Resultant Image Obtained
by the subtraction
of the above images
is as: |
|
 |
|
| Sample
Project |
|
| Please
Review other articles
based on Logical Operators
to get the better
understanding of the
project. The application
seems to be in this
GUI. |
|
 |
|
| The
project is a part
of the series of the
image processing articles
written just for the
prosperity and help
for the students searching
for Image Processing
free stuff. |
|
Download
Project Files
 |
|
| Image
Processing Articles
Index |
