| Image
Processing Articles
Index |
 |
| Background |
| The
NOT binary operation
takes one binary input
and outputs 1 when
the input is 0 and
the output is 0 only
if the input is 1.
This functionality
is shown by the help
of the following table: |
|
 |
| NOT |
|
| Using
NOT boolean algebra
allows you to represent
things like: |
|
| The
sky is high and blue |
|
| Understanding
NOT Mathematically: |
| The
NOT of two images
is carried out by
performing the inversion
operation on the corresponding
pixels of the two
images to produce
the output pixel value.
For instance, suppose
that we wish to NOT
the integer 167 using
8-bit integers. 167
is 10100111 in binary.
Inverting these together
in bitwise fashion,
we have 01011000 in
binary or 88 in decimal. |
|
| General
Working |
| The
NOT operations are
performed through
a single pass module
which during operation
passes through the
each pixel of the
image and calculates
the pixels of the
output image by doing
the respective operation
on the corresponding
pixel to calculate
the output pixels.
|
|
| Each
pixel in the input
image having a logical
1 (often referred
to as foreground)
has a logical 0 (associated
with the background
in the output image
and vice versa. Hence,
applying logical NOT
to a binary image
changes its polarity
. The logical NOT
can also be used for
a graylevel image
being stored in byte
pixel format by applying
it in a bitwise fashion.
The resulting value
for each pixel is
the input value subtracted
from 255: |
|
| O(
i , j ) = 255 - I(
i , j ) |
|
| If
this output image
is normalized for
an 8-bit display,
we again obtain the
photographic negative
of the original input
image. |
|
| Guidelines
for Use |
| When
the invert operator
is applied on the
image: |
|
 |
|
| the
following result is
obtained: |
|
 |
|
| The
inversion technique
can be used to get
the negative of the
image. This can be
seen by applying the
invert technique on
the following image:
|
|
 |
|
| The
following negative
is obtained: |
|
 |
|
| C#
Sample Program: |
|
| The
algorithm is coded
in C# using unsafe
so the quality and
speed of the program
may not be affected.
The class BitmapData
is used to read and
process the pixels
in the image. This
is the speicality
of C# to provide such
a speed even on image
processing applications.
There is a set of
modules that are designed
to implement the algorithm.
The program expects
that the input images
are grayscaled. Then
it takes the BitmapData
objects of the two
input images. It then
subtracts the input
pixel from 255( 11111111
) to calculate the
output pixel. |
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