Princess Noura University

Digital Image Processing

Mid-Term 1 (Solution)

Name: _______________________ Group: _____________ Grade: ________/15

Q1) Choose the correct answer of the following: ()

1. The bitmap representation is:

a) A 2D function f(x,y) that can be observed by human visual system.

b) It is also called “raster or pixel maps” representation.

c) It is an image that is broken up into a grid.

d) b + c

2. Operates on single pixels of an image, for the purpose of enhancing that image:

a) Intensity transformations

b) Spatial filtering

c) Intensity level slicing

d) Bit-Plane Slicing

3. Highlighting the contribution made to total image appearance by specific bits:

a) Intensity level slicing

b) Bit-Plane Slicing

c) Image Negatives

d) None of the above

4. If the gray levels of an image are distributed at the left most of a histogram of an image that means that the image has:

a) a high contrast image

b) a low contrast image

c) a dark image

d) a bright image

Q2) Select (T-True) for Correct statement and (F-False) for incorrect answer and correct the wrong answer:

1. In image acquisition the images can be obtained from digital cameras, scanners, MRI and Ultrasound imaging, and Infrared and Microwave imaging.

( T )

2. False contouring is caused by large number of gray scale levels. ( F )

insuffecient

3. Intensity-level slicing is highlighting a specific range of intensities in an image often is of interest. ( T )

4. low-contrast images can result from poor illumination, lack of the dynamic range in the imaging sensor, or even the wrong setting of the lens aperture during image acquisition ( F )

Q3) Discuss the following pictures in means of:

a. The Transformation function applied to each picture

b. The result of the transformation function applied

a. The transformation function applied is the power-law function.

b. It results of darkening the bright image using values of Gamma > 1.

(a. The transformation function applied is the contrast stretching function.b. In the first picture is the original picture resulting from low contrast, the second picture is a result of contrast stretching and it produces an enhanced image since the range of intensity levels was expanded. The third image results in thresholding after applying the contrast stretching function where the values of r1= r2 and s1=0 and s2=L-1.)

Q4) suppose that a 3-bit (L=8) image of size 64*64 (4096) has the following intensity distribution nk = (150, 762, 900, 237,850, 623, 300, 274).

1- Draw the histogram for the given input after filling the following table:

Pr(rk) = nk/mn

nk

rk

0.04

150

R0

0.19

762

R1

0.22

900

R2

0.06

237

R3

0.21

850

R4

0.15

623

R5

0.07

300

R6

0.07

274

R7

2- Find the equalized values (sk) after applying the histogram equalization function on the previous values.

S0 = 7*0.04 = 0.28 0-

2 1.61= 7* (0.04+0.19)= S1 -

3S2 = 7 * (0.04+0.19+0.22) = 3.15 -

4S3 = 7*(0.04+0.19+0.22+0.06) = 3.57 -

57*(0.04+0.19+0.22+0.06+0.21) = 5.04 = S4 -

67*(0.04+0.19+0.22+0.06+0.21+0.15) = 6.12 = S5 –

77*(0.04+0.19+0.22+0.06+0.21+0.15+0.07) = 6.58 = S6 –

7S7 = 7*(0.04+0.19+0.22+0.06+0.21+0.15+0.07+0.07) = 7.1 -

3- Draw the equalized histogram (the output histogram after equalization).

S0 = 0= r0 = 0.04

S1 = 2= r1 = 0.19

S2= 3= r2 = 0.22

S3= 4= r3 = 0.06

S4= 5= r4 = 0.21

S5= 6= r5 = 0.15

S6= 7= r6 = 0.07

S7= 7= r7 = 0.07

Pr(rk) = nk/mn012345674.0000000000000008E-20.190.226.0000000000000005E-20.210000000000000020.150000000000000027.0000000000000021E-27.0000000000000021E-2Pr(sk) 02345674.0000000000000008E-20.190.226.0000000000000005E-20.210000000000000020.150000000000000020.14000000000000001Column20234567Column10234567

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