Veja grátis o arquivo Apostila VisualG completa enviado para a disciplina de Programação I Categoria: Outros – 8 – O visualg é uma das melhores ferramentas que existem para aprender a programar. Aprenda agora a programar no visualg com o melhor material da web. O Visualg é um programa que permite criar, editar, interpretar e que também executa os algoritmos em português estruturado (portugol) como se fosse um.

Author: Meztijind Gogore
Country: Gambia
Language: English (Spanish)
Genre: Education
Published (Last): 25 May 2005
Pages: 18
PDF File Size: 8.95 Mb
ePub File Size: 4.22 Mb
ISBN: 182-8-59441-761-3
Downloads: 37645
Price: Free* [*Free Regsitration Required]
Uploader: Akihn

Suppose we have visulag event A, which is a set of outcomes of some random experiment. We can take advantage of this form of redundancy by constructing a list of these words and then represent them by their position in the list. The width of the critical band varies with frequency. One way to improve what you see in low light is to focus to one side of the object.

Vsiualg, the eye adapts to an average brightness level. Introdution to Data Compression de Khalid Sayood We can use this knowledge to design compression systems such that the distortion introduced by our lossy compression scheme is not noticeable.

download do VisualG

For example, we cannot hear the very high frequency sounds that dogs can hear. Notice that the sequence is made up of eight different symbols.

The sequence does not seem to follow a simple law as in the previous case. Lossless compression is generally used for applications that cannot tolerate any difference between the visualy and reconstructed data.

Apostila Visualg

The tympanic membrane and the bones convert the pressure waves in the air to acoustical vibrations. Suppose we send the first value, then in place of subsequent values we send the difference between it and the previous value. In brief, data compression is the art or science of representing information in a fisualg form.

Lossy compression techniques involve some loss of information, and visualb that have been compressed using lossy techniques generally cannot be recovered or reconstructed exactly. Esse site utiliza cookies.


Curso de Sistemas de Informação |

Obviously, Sherlock Holmes understood information theory! Although the idea of a quantitative measure of information apsotila been around for a while, the person who pulled everything together into what is now called information theory was Claude Elwood Shannon, an electrical engineer at Bell Labs.

The rods are more sensitive to light than cones, and in low light most of our vision is due to the operation of rods. Although this equivalence of the mathematical and semantic definitions of information holds true most of the time, it does not hold all of the time.

Listen to music on your mp3 player or watch a DVD and you are being entertained courtesy of compression. The muscles of the eye move the eyeball, positioning the image of the object on the fovea. This way the object is imaged on the rods, which are more sensitive to light. The ratio y is known as the Weber fraction or Weber ratio.

However, at a given instant we cannot perceive the entire range of brightness. The sequence of transmitted values would be.

Curso de Informática e Computação |

For most frequencies, when the noise just masks the tone, the ratio of the power of the tone divided by the power of the noise in apostial critical band is a constant [97]. Suppose we aposfila the following sequence: There are three kinds of cones, each of which are most sensitive at different wavelengths of the visible spectrum. The sequence of transmitted visyalg would be Vosualg 1.

Similarly, when viewing a reconstruction of a video sequence, the fact that the reconstruction is different from the original is generally not important as long as the differences do not result in annoying artifacts. Even if we ignore the mathematical definition of information and simply use the definition we use in everyday language, this makes some intuitive sense.

The range decreases with age; older people are usually unable to hear the higher frequencies. The reason we need data compression is that more and more of the information that we generate and use is in digital form—in the form of numbers represented by bytes of data.


Download do Visualg 2. In many applications, this lack of exact reconstruction is not a problem. This becomes a drawback in low light. As there are 41 symbols in the sequence, this works aposfila to approximately 2.

And the number of bytes required to represent multimedia data can be huge. Ele indicou este curso como um ponto de partida. The ear is divided into aplstila parts, creatively named the outer ear, the middle ear, and the inner ear.

How does this description of the human visual system relate to coding schemes? In order to represent eight symbols, we need to use 3 bits per symbol. As in vision, auditory perception has several visuwlg components. The fact that one sound can drown out another seems reasonable. Introdution to Data Compression.

Text compression is an important area for lossless compression. The cones are mostly concentrated in a very small area of the retina called the fovea.

The retina contains two kinds of receptors, called rods and cones. The limitations of auditory perception play a major role in the design of audio compression algorithms. The inner ear contains, among other things, a snail-shaped passage called the cochlea that contains the transducers that convert the acoustical vibrations to nerve impulses.

This membrane separates the outer ear from the middle ear. For example, in order to digitally represent 1 second visuslg video without compression using the CCIR formatwe need more than 20 megabytes, or megabits. The eye is a globe-shaped object with a lens in the front that focuses objects onto the retina in the back of the eye. This ratio is known to be constant at about 0.