Advanced Digital Image Processing
(CE 40-823)
Assignment No. 2
Due time: 1385/8/16
NOTE:
Read the “HW_important notes.doc” file (in the course web page resource folder)
Those reports which have not the specified properties may not be considered.
1- solve the following problems from text book:
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3.2
3.6
3.7
2- Develop code to extract the three planes corresponding to R, G, and B out of the
given image. Write code to return error messages if the image is an indexed or gray–
scale one.
3- Develop code for visualizing the input function f:R2 -> R3 for a given domain.
Suppose the output vector of function as an a) RGB vector b)HSV vector and display
the image. (show your result for a sample function)
4- Consider a simple pixel based image enhancement process such as contrast
stretching (chapter 7.2 in the text book, equation 7.2 , Figure 7.2).
a) Apply the function on R,G and B channels separately and display the original
image and the processed one for each channel. Explain the result.
b) Consider the output of previous step as a new RGB image and display it. Explain
the result. Do you agree with the depicted diagram in Fig 7.40 in the text book?
(Note: Don’t worry! The knowledge of chapter 7 is not required for solving this
question.)
Hint:
There are several color coordinate systems, which have come to existence for a variety of
reasons. Most computer displays use either 8, 16, or 24 bits per screen pixel. The number
of bits per pixel determines how many different colors the system can display.
A 24-bit display provides optimal color resolution. It uses 8 bits for each of the three
color components. To determine your system’s color depth, enter this command at the
MATLAB prompt:
get (0.’ScreenDepth’)
Regardless of the number of colors your system can display, MATLAB can store and
process images with up to 224 colors.
The image processing toolbox represents color as RGB values, either directly or
indirectly. In order to change the color coordinate system, MATLAB supports some of
the common systems:
1. National Television Systems Committee (NTSC)
2. YCbCr
3. Hue, Saturation, Value (HSV)
There are some predefined functions in MATLAB used for the purpose of converting one
system (mostly RGB) to other systems; rgb2ntsc, rgb2ycbcr, and rgb2hsv.