Digital Image Processing : Sample Practise Questions

The following questions have numbering for each section. Ignore the numbering and try to find answers for the given questions.

1. Draw the cross section of the human eye.
2. Explain- photopic or bright-light vision.
3. Explain-scotopic or dim-light vision.
4. What is called blind spot in the eye?
5. The observer is looking at a tree 15m high at a distance of 100m. Find the size of the retinal image.
6. Define Weber ratio.
7. Explain image formation in the eye.
8. What is brightness adaptation?
9. What is brightness discrimination?
10. What is Mach band pattern?
11. Explain simultaneous contrast.
12. How a digital image is represented?
13. What do you mean by a pixel?
14. What are called 4-neighbors of a pixel?
15. What are diagonal neighbors of a pixel?
16. Define 4-connectivity.
17. Define 8-connectivity.
18. Define m-connectivity.
19. What is called Euclidean distance?
20. What is called D4 distance or city-block distance? 
21. What is called D8 distance or chess board distance?
22. Give any four arithmetic operators with pixels.
23. Give any four logical operators with pixels.
24. What is meant by perspective transformation?
25. What is called camera calibration?.
26. What do you mean by stereo imaging?
27. What is called gray scale?

1. Explain in detail the elements of Digital Image Processing systems.
2. Explain in detail the structure of the human eye.
3. Explain image formation in the eye, brightness adaptation and discrimination.
4. Explain any four basic relationships between pixels.
5. Using perspective transformation and assuming the world coordinate system is aligned with the camera coordinate system, derive expression for x,y,z.
6. Using perspective transformation and assuming the world coordinate system is aligned with the camera coordinate system, derive expression for X,Y,Z.
7. Explain the basic transformations: translation, scaling, rotation, concatenation and inverse transformation.

1. Define a two dimensional bandlimited image.
2. Define Nyquist rate.
3. What is aliasing? Explain it with image spectrum.
4. What are called fold over frequencies?
5. Define sampling theorem.
6. List the practical limitations in sampling and reconstruction.
7. What is Moiré effect?
8. Write a note on display aperture.
9. What is quantization? How it is applied in images?
10. List the properties of the optimum mean square Quantizer.
11. What will be the mean square error for uniform PDF Optimal Quantizer?
12. What is meant by visual quantization?
13. How to reduce the contouring effect in visual quantization?
14. Draw the block diagram of Contrast quantization.
15. Draw the block diagram of pseudo random noise quantization.
16. What is a compandor?

1. Explain 2-D sampling theory in detail.
2. Explain in detail the practical limitations in sampling and reconstruction.
3. Explain the optimum mean square or Lloyd-max quantizer in detail.
4. Explain in detail about visual quantization.
5. Explain the process of reconstruction of an image from its samples.
6. Explain compandor design.

1) Properties of Fourier Transform?
2) Write the equation for 2D Fourier transform and Inverse Fourier transform?
3) Write the equation for the 2-D convolution?
4) Properties of convolution?
5) Define orthogonal matrix and unitary matrix?

7) If A and B are M1 xM2 and N1 xN2 matrices respectively, find their Kronecker product.
8) Define Kronecker Product?
10) Define the mean and co-variance of random signal?
11) For a given orthogonal matrix A and image U, 
Find the transformed image and the inverse transformation.
12) Write the equation for the 2-D orthogonal and unitary transforms?
13) Give some properties of 2-D DFT?
14) Write the equation for 2-D IDFT?
15) Mention the properties of Discrete cosine transform.
16) Define DCT?
17) Define Sequency?
18) Properties of Hadamard Transform?
19) For the 2x2 transform A and the image U

Calculate the transformed image V and the basis images.
20) What is Walsh transform?
21) Give some properties of 2-dimensional DFT?
22) What are the properties of walsh transform?
23) What is Haar Transform?
24) What is Hadamard transform?
25) Write the properties of Haar transform?
26) What is slant transform?
27) What are the properties of slant transform?
28) What is KL transform?
29) What are the properties of KL transform?
30) Compare KL, Hadamard, Haar and slant transform?


1) Find the Fourier spectrum , phase angle and power spectrum of 2D Fourier transform.
2) Write the DFT for the 2-variable? Find the DFT for the following sequence {2,3,4,4} and find its fourier spectrum?
3) Explain the following DFT properties:
a) Separability b) Translation
c) Rotation d) Distributivity & scaling
4) Explain the following (a) Convolution (b) Correlation
5) Develop an FFT algorithm for a 2-D transform? How many additions & multiplication are needed to compute 2D FFT of an N x N image?
6) Obtain the Haar transform matrix for N=4?
7) Obtain the Haar transform matrix for N=8?
8) Obtain the slant transform matrix for N=4?
9) Obtain the slant transform matrix for N=8?
10) Obtain the Hadamard transform matrix for N=4?
11) Obtain the Hadamard transform for N=8?
12) Obtain the Walsh transform matrix for N=4?


Part- A
1. What is image enhancement? What are the types of enhancement available?
2. What is point processing?
3. What is contrast stretching? Why is it required?
4. What is the need for reducing the dynamic range of image?
5. What is gray level slicing?
6. What is bit plane slicing?
7. What is histogram?
8. What is histogram equalization?
9. Draw the histogram for bright image and low contrast image?
10. Give the steps in histogram specification?
11. What is spatial filtering?
12. What are the effects of low pass and high pass filtering of images?
13. What is image smoothening? What are the types available?
14. Explain high boost filtering.
15. Draw the mask for different derivative filters.
16. What is homomorphic filtering?
17. Differentiate restoration and enhancement.
18. What is circulant and block-circulant matrices.
19. What is meant by diagonalization? Why is it required?
20. What is meant by algebraic approach to restoration? What are the types?
21. What is constrained and unconstrained restoration?
22. What is inverse filtering?
23. Write the equation for wiener filter.
24. What is parametric wiener filter?
25. What is rubber sheet transformation?
26. What are the basic operations in geometric transformation?
27. What is Gray- level interpolation?

Part –B
1) Explain the different point processing techniques used for image enhancement.
2) With neat diagram histogram processing and Equalization.
3) Explain histogram specification.
4) Explain the various types of image smoothening filters.
5) Explain in detail about homomorphic filtering.
6) Explain the concept of degradation model.
7) Explain discrete formulation of degradation model.
8) Describe the process involved in diagonalisation of circulant and block circulant matrices.
9) Explain constrained and unconstrained algebraic approach in detail.
10) Explain inverse filtering in detail.
11) Explain weiner filter in detail.
12) Write notes on Geometric transformation.