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Computer Graphics Lab Viva Questions And Answers Part 1

CG LAB EXAM VIVA QUESTIONS.

  • What is scan conversion?
    A major task of the display processor is digitizing a picture definition given in an application program into a set of pixel-intensity values for storage in the frame buffer. This digitization process is called scan conversion
  • Write the properties of video display devices?
    Properties of video display devices are persistence,resolution, and aspect ratio
  • What is rasterization?
    The process of determining the appropriate pixels for representing picture or graphics object is known as rasterization
  • Define Computer graphics.
    Computer graphics remains one of the most existing and rapidly growing computer fields. Computer graphics maybe defined as a pictorial representation or graphicalrepresentation of objects in a computer.
  • Name any four input devices
    Four input devices are keyboard, mouse, image scanners,and trackball.
  • Write the two techniques for producing color displayswith a CRT?
    Beam penetration method, shadow mask method
  • What is vertical retrace of the electron beam?
    In raster scan display, at the end of one frame, the electronbeam returns to the left top corner of the screen to startthe next frame
  • Short notes on video controller?
    Video controller is used to control the operation of thedisplay device. A fixed area of the system is reserved forthe frame buffer, and the video controller is given directaccess to the frame buffer memory
  • What is bitmap?
    Some system has only one bit per pixel; the frame buffer isoften referred to as bitmap.
  • Differentiate plasma panel display and thin film electroluminescent display?
    In plasma panel display, the region between two glassplates is filled with neon gas. In thin film electroluminescent display, the region between two glassesplates are filled with phosphor, such as zinc sulphide dopedwith manganese.
  • What is resolution?
    The maximum number of points that can be displayedwithout overlap on a CRT is referred to as the resolution.
  • What is horizontal retrace of the electron beam?
    In raster scan display, the electron beam return to the leftof the screen after refreshing each scan line, is called horizontal retrace of the electron beam.
  • What is filament?
    In the CRT, heat is applied to the cathode by directing acurrent through a coil of wire, is called filament
  • What is pixmap?
    Some system has multiple bits per pixel, the frame buffer isoften referred to as pixmap.
  • Write the types of clipping?
    Point clipping, line clipping, area clipping, text clipping andcurve clipping.
  • What is meant by scan code?
    When a key is pressed on the keyboard, the keyboardcontroller places a code carry to the key pressed into a partof the memory called as the keyboard buffer. This code iscalled as the scan code.
  • List out the merits and demerits of Penetrationtechniques?
    The merits and demerits of the Penetration techniques areas follows. It is an inexpensive technique. It has only four colors. The quality of the picture is not good when it is comparedto other techniques. It can display color scans in monitors. Poor limitation etc.
  • List out the merits and demerits of DVST?
    The merits and demerits of direct view storage tubes[DVST] are as follows. It has a flat screen. Refreshing of screen is not required. Selective or part erasing of screen is not possible. It has poor contrastPerformance is inferior to the refresh CRT.
  • What do you mean by emissive and non-emissivedisplays?
    The emissive display converts electrical energy into lightenergy. The plasma panels, thin film electro-luminescentdisplays are the examples.The Non-emissive are optical effects to convert the sunlightor light from any other source to graphic form. Liquidcrystal display is an example
  • List out the merits and demerits of Plasma paneldisplay?
    Merits. Refreshing is not required. Produce a very steady image free of Flicker. Less bulky than a CRT.Demerits. Poor resolution of up to 60 d.p.i. It requires complex addressing and wiring. It is costlier than CRT.
  • What is persistence?
    The time it takes the emitted light from the screen to decayone tenth of its original intensity is called as persistence.
  • What is Aspect ratio?
    The ratio of vertical points to the horizontal pointsnecessary to produce length of lines in both directions ofthe screen is called the Aspect ratio. Usually the aspectratio is ¾.
  • What is the difference between impact and non-impactprinters?
    Impact printer press formed character faces against aninked ribbon on to the paper. A line printer and dot-matrixprinter are examples.Non-impact printer and plotters use Laser techniques,inkjet sprays, Xerographic process, electrostatic methodsand electro thermal methods to get images onto thepapers. Examples are: Inkjet/Laser printers.
  • Define pixel?
    Pixel is shortened forms of picture element. Each screenpoint is referred to as pixel or pel.
  • What is frame buffer?
    Picture definition is stored in a memory area called framebuffer or refresh buffer.
  • Where the video controller is used?
    A special purpose processor, which is used to control theoperation of the display device, is known as videocontroller or display controller.
  • What is run length encoding?
    Run length encoding is a compression technique used tostore the intensity values in the frame buffer, which storeseach scan line as a set of integer pairs. One number eachpair indicates an intensity value, and second numberspecifies the number of adjacent pixels on the scan linethat are to have that intensity value.
  • What is point in the computer graphics system?
    The point is a most basic graphical element & is completelydefined by a pair of user coordinates (x, y).
  • Write short notes on lines?
    A line is of infinite extent can be defined by an angle ofslope q and one point on the line P=P(x,y). This can also bedefined as y=mx+C where C is the Yintercept.
  • Define Circle?
    Circle is defined by its center xc, yc and its radius in usercoordinate units. The equation of the circle is (x-xc) + (yyc)= r2.
  • What are the various attributes of a line?
    The line type, width and color are the attributes of the line.The line type include solid line, dashed lines, and dottedlines.
  • What is antialiasing?
    The process of adjusting intensities of the pixels along theline to minimize the effect of aliasing is called antialiasing.
  • What is Transformation?
    Transformation is the process of introducing changes in theshape size and orientation of the object using scalingrotation reflection shearing & translation etc.
  • What is translation?
    Translation is the process of changing the position of anobject in a straight-line path from one coordinate locationto another. Every point (x , y) in the object must under go adisplacement to (x|,y|). the transformation is:x| = x + tx ; y| = y+ty
  • What is rotation?
    A 2-D rotation is done by repositioning the coordinatesalong a circular path, in the x-y plane by making an anglewith the axes. The transformation is given by:X| = r cos (q + f) and Y| = r sin (q + f).
  • What is scaling?
    A 2-D rotation is done by repositioning the coordinatesalong a circular path, in the x-y plane by making an anglewith the axes. The transformation is given by:X| = r cos (q + f) and Y| = r sin (q + f).
  • What is shearing?
    The shearing transformation actually slants the objectalong the X direction or the Y direction as required. ie; thistransformation slants the shape of an object along arequired plane.
  • What is reflection?
    The reflection is actually the transformation that producesa mirror image of an object. For this use some angles andlines of reflection.
  • What are the two classifications of sheartransformation?
    X shear, y shear
  • A point (4,3) is rotated counterclockwise by an angle of45°. Find the rotation matrix and the resultant point
.
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