Digital Image

Digital Image

Paper details:
just write introduction about the digital image , the SciLab program

Aim
To improve the
visual display of an image by Contrast S
tretching.
Procedure
Write a
SciLab
program
to:
(1)  Read, display and contrast stretch an image as
follows:

P
rompt the user to enter
the filename of an image,

read
and display
the image
(before stretching)
,

create
and plot
a histogram of the image,

contrast stretch the image to
256 grey

levels by changing the actual image pixel values,

display the stre
tched image, and

create a
nd plot a
histo
gram of the stretched image.
(2)  Repeat the above but stretch the displayed image by changing the look

up table (i.e. the
colormap
) rather than changing the actual pixel values of the image.
The image you are to use is
skull_xray_1.bmp
and it can b
e downloaded from the PCN112
Blackboard
web site.
Note
s
.
(1) The
imshow(
)
function (part of
imtools.sci
)
assumes that the pixel values are in the range 0 to
255
and displays the image using 256 grey levels.
You can download
imtools.sci
from the
PCN112
Blackboard
web site.
(2) You have
to
create more that 1 histogram, so it would be a good idea to write the histogram
part of your program as a function.
(You can lo
ok at the code for
imtools
to see how to make a
function.)
What to s
ubmit
Your
report should include:

a well

commented source listing of your program

a presentation of your results, i.e. copies of the images, histograms and graphs of the LUTs,
and

a
discussion of the results.
In the discussion you should describe the appearances of the original and enhanced images and
those features/shapes of the histograms and LUTs that relate to the contrast enhancement. The
aim of the assignment is to compare two
methods of contrast enhancement so therefore the
relative merits (i.e. advantages and/or disadvantage) of each method should be discussed.
Please email me a copy of your program so that I can run it if necessary.
Christian Langton
September 2015