Page 41 - DCAP504_Computer Graphics

Computer Graphics

image (negative image). Once the negative is ready, it is processed and transferred onto a photographic
paper. An optical apparatus, known as the enlarger, is used to project the image of the negative onto a
base, and finely control the focus, amount, and duration of light incident on the paper. A sheet of
photographic paper is then exposed to the enlarged image that projects from the negative.
During exposure, the dodging and burning techniques are used to adjust values of the image. The
processes involved in these include reducing and increasing the amount of incident light selectively for
part or all of the exposure time. After exposure, the photographic printing paper is ready to be
processed. The photographic paper is processed using chemicals in the following order:
1. Developing the print using a photographic developer
2. Rinsing with stop-bath
3. Fixing the image permanently with the use of photographic fixer
4. Washing to remove all the processing chemicals
5. Drying
In this sub-section we discussed the evolution of megapixel. Let us now discuss what a frame buffer is
and the types of frame buffer.
3.6 Frame Buffer
Frame buffer refers to the part of memory that is reserved for holding the entire bit-mapped image that
is sent to the monitor. The frame buffer is typically stored in the memory chip on the video adapter.
However, in some cases the frame buffer is stored in the main memory, and the video chipset is
integrated into the motherboard design.
In a raster scan display system, the storage area is arranged as a two-dimensional table. Every row-
column entry stores information such as brightness and/or color value of the corresponding pixel on
the screen. In a frame buffer, 1 to 24 or more bits represent each pixel depending on the quality
(resolution) of the display system and certain attributes of the pixel. A higher resolution gives better
quality of the display or graphics.
Commands to plot a point or line are converted into intensity and color values of the pixel array or
bitmap of an image by a process called Scan Conversion. Figure 3.7 depicts the frame buffer using eight
5-bit shift registers.

Figure 3.7: Frame Buffer Using Eight 5-bit Shift Registers

Source: Computer Graphics & Multimedia First Ediction-2009, Godse. A.P & Godse. D.A, Technical Publications,
Chapter 1, Page 56
The refresh buffer in the display system, cycles row by row at speeds of 30 or 60 times per second to
display the image. The digital/analog converter, which produces the necessary deflection signals to
generate the raster scan, routes the intensity values picked up from the frame buffer. Interlacing
produces a flicker-free image. First, it displays all odd-numbered scan lines from top to bottom and then

34 LOVELY PROFESSIONAL UNIVERSITY