Flowchart: Alternate Process: DECEMBER 2008Code: AT14                                                                            Subject: IMAGE PROCESSING &

                                                                                                               COMPUTER GRAPHICS

Time: 3 Hours                                                                                                     Max. Marks: 100

 

NOTE: There are 9 Questions in all.

·      Question 1 is compulsory and carries 20 marks. Answer to Q. 1. must be written in the space provided for it in the answer book supplied and nowhere else.

·      Out of the remaining EIGHT Questions answer any FIVE Questions. Each question carries 16 marks.

·      Any required data not explicitly given, may be suitably assumed and stated.

 

 

Q.1       Choose the correct or best alternative in the following:                                         (2x10)

       

             a.  The _________ method for displaying color pictures has been used with random-scan monitors.

 

                  (A) Beam-penetration                           (B) Shadow-mask

                  (C) Emissive                                         (D) Nonemissive

 

             b.  A transformation that distorts the shape of an object such that the transformed shape appears as if the object were composed of internal layers that had been caused to slide over each other is called a _________.

 

                  (A) Rotation                                         (B) Shear

                  (C) Reflection                                       (D) Translation

 

             c.  Having a jagged or stair step appearance of lines is known as  

 

                  (A) Scanning                                        (B) Aliasing

                  (C) Anti-aliasing                                   (D) Persistence

 

             d.  The point for any set of lines that are parallel to one of the principal axes of an object is referred to as a _________.

 

                  (A) Viewing point                                 (B) Elevation point

                  (C) Clipping point                                 (D) Principal vanishing point

 

             e.  The matrix denotes the following transformation.

 

                  (A) Reflection about the x-axis              (B) Reflection about y = x

                  (C) Reflection about the y-axis              (D) Reflection about y = -x

 

             f.   _________  refers to the smallest discernible change in gray level.

 

                  (A) Spatial resolution                            (B) False contouring

                  (C) Gray level resolution                       (D) Checkerboard pattern

 

             g.  These filters are particularly effective in the presence of impulse noise.

 

                  (A) Sharpening                                     (B) Median filters

                  (C) Edge detection                               (D) Min filters

 

             h.  Computing the 1D Fourier transform of M points using FFT requires _________ operations.

 

                  (A) M2                                                 (B) M/2

                  (C) Mlog2M                                         (D) M2log2M

 

             i.   This edge detection mask has slightly superior noise-suppression characteristics.

 

                  (A) Prewitt mask                                  (B) Roberts mask

                  (C) Averaging mask                              (D) Sobel mask

 

             j.   Portable Document Format (PDF) uses this compression technique.

 

                  (A) Huffman coding                              (B) Arithmetic coding

                  (C) Bit plane coding                              (D) LZW coding

 

 

Answer any FIVE Questions out of EIGHT Questions.

Each question carries 16 marks.

 

                  

  Q.2     a.   Write short notes on (i) Mouse (ii) Digitizing Tablet (iii) Light pens.                      (8)

 

             b.   Find the line segment joining the points (–2, 1) and (2, 3) using the Bresenham line generation algorithm.                                                           (8)

 

  Q.3     a. With suitable diagram derive the transformation matrix for a counterclockwise rotation about a point (x, y).                                                           (8)

 

             b.   Find the transformation matrix corresponding to reflection of an object with respect to a line y = x – 5.                                                                   (8)

 

  Q.4     a.   Consider the clipping window with diagonally opposite edges (1, –1) and (–1, 1). Using Cohen Sutherland line clipping algorithm, slip the line with end points  (–3/2, –1) and (3/2, 2). Explain with a figure also.                                                           (8)

 

             b.   What is hierarchical z-buffer algorithm? How does it differ from classical z-buffer algorithm?                                                                      (8)

 

  Q.5     a. Explain homogeneous coordinates. Describe how the transformation happens from world coordinates to viewing coordinates.                            (8)

 

             b.   Describe the following projections

                   (i) Parallel projection                            (ii) Orthographic projection

                   (iii) Perspective projection.                                                                                 (8)

  Q.6     a.   HDTV generates images with a resolution of 1125 horizontal TV lines interlaced where every other line is painted on the tube face in each of two fields, each field being 1/60th of a second in duration. The width-to-height aspect ratio of the images is 16:9. Each pixel in the color image has 24 bits of intensity resolution, 8 pixels each for a red, a green, and a blue image. How many bits would it take to store a 2-hour HDTV program?                                              (8)

 

             b.   Explain the histogram equalization technique for image enhancement.                   (8)

 

  Q.7     a.   Explain the following filters in spatial domain. (i) Unsharp masking filter (ii) High-Boost filter. Give a 3 x 3 mask for performing unsharp masking and high boost filtering in a single pass through an image.       (8)

 

             b.   Explain 2D Fourier transform giving the equations of forward and inverse transform. Explain the following properties: (i) Translation (ii) Separability (iii) Periodicity and conjugate symmetry. (8)

 

  Q.8     a.   Explain the LZW algorithm and encode the 7-bit ASCII string aaaaaaaaaaa.                       (8)

 

             b.   With the help of an example, explain error-free compression technique that uses variable-length coding.                                                                 (8)

 

  Q.9     a.   Describe the thresholding method for image segmentation. Explain the basic global thresholding technique by providing the algorithm.                        (8)

 

             b.   Explain the following:

                   (i) Laplacian of Gaussian operator for edge detection

                   (ii) Line detection.                                                                                              (8)