DIGITAL IMAGE PROCESSING INTERVIEW QUESTIONS & ANSWERS

 

1. Question 1. Define Image?

   Answer :

   An Image may be defined as a two dimensional function f (x,y) where x & y are spatial (plane) coordinates, and the amplitude of f at any pair of coordinates (x,y) is called intensity or gray level of the image at that point. When x,y and the amplitude values of f are all finite, discrete quantities we call the image as Digital Image.

2. Question 2. Define Image Sampling?

   Answer :

   Digitization of spatial coordinates (x,y) is called Image Sampling. To be suitable for computer processing, an image function f(x,y) must be digitized both spatially and in magnitude.

3. Question 3. Define Quantization ?

   Answer :

   Digitizing the amplitude values is called Quantization. Quality of digital image is determined to a large degree by the number of samples and discrete gray levels used in sampling and quantization.

4. Question 4. What Is Dynamic Range?

   Answer :

   The range of values spanned by the gray scale is called dynamic range of an image. Image will have high contrast, if the dynamic range is high and image will have dull washed out gray look if the dynamic range is low

5. Question 5. Define Mach Band Effect?

   Answer :

   The spatial interaction of Luminance from an object and its surround creates a Phenomenon called the mach band effect.

6. Question 6. Define Brightness?

   Answer :

   Brightness of an object is the perceived luminance of the surround. Two objects with different surroundings would have identical luminance but different brightness.

7. Question 7. Define Tapered Quantization?

   Answer :

   If gray levels in a certain range occur frequently while others occurs rarely, the quantization levels are finely spaced in this range and coarsely spaced outside of it.This method is sometimes called Tapered Quantization.

8. Question 8. What Do You Meant By Gray Level?

   Answer :

   Gray level refers to a scalar measure of intensity that ranges from black to grays and finally to white.

9. Question 10. Write The M X N Digital Image In Compact Matrix Form?

   Answer :

   f(x,y )= f(0,0) f(0,1)………………f(0,N-1)

   f(1,0) f(1,1)………………f(1,N-1)

   .

   .

   .

   f(M-1) f(M-1,1)…………f(M-1,N-1)

10. 1. Question 11. Write The Expression To Find The Number Of Bits To Store A Digital Image?

       Answer :

       The number of bits required to store a digital image is

       b=M X N X k

       When M=N, this equation becomes

       b=N^2k

    2. Question 12. What Do You Meant By Zooming Of Digital Images?

       Answer :

       Zooming may be viewed as over sampling. It involves the creation of new pixel locations and the assignment of gray levels to those new locations.

    3. Question 13. What Do You Meant By Shrinking Of Digital Images?

       Answer :

       Shrinking may be viewed as under sampling. To shrink an image by one half, we delete every row and column. To reduce possible aliasing effect, it is a good idea to blue an image slightly before shrinking it.

    4. Question 14. Define The Term Radiance?

       Answer :

       Radiance is the total amount of energy that flows from the light source, and it is usually measured in watts (w).

    5. Question 15. Define The Term Luminance?

       Answer :

       Luminance measured in lumens (lm), gives a measure of the amount of energy an observer perceiver from a light source.

    6. Question 16. What Is Image Transform?

       Answer :

       An image can be expanded in terms of a discrete set of basis arrays called basis images. Unitary matrices can generate these basis images. Alternatively, a given NXN image can be viewed as an N^2X1 vectors. An image transform provides a set of coordinates or basis vectors for vector space.

    7. Question 17. What Are The Applications Of Transform?

       Answer :

       1. To reduce band width
       2. To reduce redundancy.
       3. To extract feature.