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.

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The outer ear consists of the structure that directs the sound waves, or pressure waves, to the tympanic membrane, or eardrum. Although the rods are more numerous than the cones, the cones provide better resolution because they are more closely packed in the fovea. The range decreases with apostilla older people are usually unable to hear the higher frequencies.

This range of frequencies is called the critical band. Introdution to Data Compression.

Apostila Visualg – video dailymotion

Sem perdas Lossless e com perdas pequenas Lossy. If we consider the number of seconds in a movie, we can easily apostkla why we would need compression.

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 the critical band is a constant [97]. Text compression is an important ivsualg for lossless compression. Lossless compression is generally used for applications that cannot tolerate any difference between the original and reconstructed data. Many times, for example, when transmitting or storing speech and images, the data are intended to be perceived by a human, and humans have limited perceptual abilities.

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In return for accepting this distortion in the reconstruction, we can generally obtain much higher compression ratios than is possible with lossless compression. Introdution to Data Compression de Khalid Sayood Ele indicou este curso como um ponto de partida. The ratio y is known as the Weber fraction or Weber ratio.


The middle ear is an air-filled cavity containing three small bones that provide coupling between the tympanic membrane and the oval window, which leads into the inner ear. This means we have obtained a compression ratio of 1.

For example, we cannot hear the very high frequency sounds that dogs can hear. Notice that the mind does not perceive everything the eye sees. The human ear can hear sounds from approximately 20 Hz to 20 kHz, a This ratio is known to be constant at about 0.

One is that loudness is a function not only of the sound level, but also of the frequency. Downloading music from a website at these rates would take a long time. Putting all of this information together, we can develop a model for monochromatic vision, shown in Figure 8.

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. 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.

The rods are more sensitive to light than cones, and in low light most of our vision is due to the operation of rods.

A Tutorial for Beginners ; -Tutorial no slideshare: If we substitute the codes for each symbol, we will use bits to encode the entire sequence. And the number of bytes required to represent multimedia data can be huge. Therefore, if the probability of an event is low, the amount of self-information associated with it is high; if the probability of an event is high, the information associated with it is low.

Suppose we have the following sequence: If the quality of the reconstructed speech is to be similar to that heard on the telephone, a significant loss of information can be tolerated. The tympanic membrane and the bones convert the pressure waves in the air to acoustical vibrations. Use your modem, or your fax machine, and you will benefit from compression. We create these compact representations by identifying and using structures that exist in the data.


For example, in order to digitally represent 1 second of video without compression using the CCIR formatwe need more than 20 megabytes, or megabits. When dealing with text, along with statistical redundancy, we also see redundancy in the form of words that repeat often. By plotting the amplitude of tones at different frequencies that sound equally loud, we get a series of curves called the Fletcher-Munson curves [96].

Listen to music on your mp3 player or watch a DVD and you are being entertained courtesy of compression. As there are 41 symbols in the sequence, this works out to approximately 2.

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Another very interesting audio phenomenon is that of masking, where one sound blocks out or masks the perception of another sound. The width of the critical band varies with frequency.

The limitations of auditory perception play a major role in the design of audio compression algorithms. Esse site utiliza cookies. The visuzlg does not seem to follow a simple law as in the previous case. Instead, the eye adapts to an average brightness level.

It is very important that the reconstruction is identical to vsualg text original, as very small differences can result in statements with very different meanings.