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pictures on the monitor a discriminability from 72 dpi to 120 dpi is used. While typing the most
widespread discriminability is 300 dpi, but for high-quality imprints on the modern coloured
printers it is possible to use greater discriminability.
The bitmapped images are more often by the scan-out of pictures and other images, by a
digital photo camera or by “fascination” of a shot of video survey. Lately for introduction of
bitmapped images to the computer digital photo- and video cameras have been widely used.
Bitmapped images can be received directly in the programs of bit-mapped graphics.
When scanning-out an image the scintiscanner breaks up a picture to the great number of
small elements (pixels) and forms a raster picture. Color of every pixel is written down in
computer’s memory by the certain amount of bits. If a picture possesses a discriminability of
800x600, these numbers represent the amount of pixels for horizontal lines (800) and for vertical
lines (600). The more pixels are in an image, the best its discriminability is on the screen. The
number of colors necessary to paint a separate pixel is determined as two in the degree of N, where
N is an amount of bits which keep colour information about a pixel. In a contrasting black-and-
white picture every pixel is encoded by one bit. Eight bits image allows to have 256 colors, and 24
bats provide more than 16 million colors in the image, that enables to work with the images of
professional quality. Depending on the discriminability of the monitor, images which have
640х480, 800х600, 1024х768 and more pixels can be on the screen. Therefore, large amount of
information is the basic problem for using bitmapped images.
Bitmapped images have another very substantial drawback: it is difficult to increase or to
diminish them to scale. When diminishing a bitmapped image a few nearby points grow into one,
that’s why legibility of small objects on the depiction is being last. The increase of an image makes
these points bigger. No additional objects can be seen when increasing a bitmapped image. When
increasing a graphic image the size of every point is increased, that’s why a step effect appears.
Making an attempt to turn an image slightly, for example with clear vertical striolas, on a small
corner, clear lines grow into "steps" and without an increase. It means that at any transformations
(turns, down-scaling, inclinations and other) in a bit-mapped graphics it is impossible to do without
distortion (it is dictated discrete nature of image).
Nevertheless than bitmapped images are widely used in the computer engineering, because
they have certain advantages — simplicity and, as a result, the possibility of technical realization of
automation of introduction process (digitisings) of graphic information. There is the developed
system of peripheral devices for introduction photos, sliding seats, pictures, water-colours and other
graphic originals. These peripheral devices are continually improved, giving possibility of more
adequate transformation of images on financial transmitters (paper, to tape et cetera) in a digital
form.
No less important advantage of pixel graphic arts there is a possibility to create and process
photo-realistic images. It is possible to get picturesque effects, for example, fog or haze, to
represent the thinnest nuances of color, create a perspective depth and unsharpness, washed out etc.
Therefore photographs and pictures, entered in a computer, are stored exactly as bitmapped
images. Most pictures in a world computer network the Internet is also bitmap files.

9.3.2 VECTOR GRAPHICS

In order to avoid the problems which arise when using bitmapped images a vectorial method
of coding images was invented.
In the vectorial method of coding geometrical figures, curves and lines which make a picture
are saved in the computer’s memory as mathematical formulas and geometrical abstractions, such
as a circle, a square, an ellipse and similar figures. For example, to code a circle, it is not needed to
be broken up to separate pixels, but it is necessary to memorize its radius, coordinates of a center
and color. For a rectangle it is enough to know the size of sides, its location and color of sketching.
Various figures can be described with the help of mathematical formulas. Some simple figures
(geometrics) are used to draw more difficult pictures.

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