1 SECTION C Chapter 1: Computers and Digital Basics 1 Digital Data Representation Data Representation Basics Representing Numbers, Text, and Pictures

1SECTION C

Chapter 1: Computers and Digital Basics 1

Digital Data RepresentationDigital Data Representation

Data Representation Basics Representing Numbers, Text, and Pictures Quantifying Bits and Bytes Circuits and Chips

1 Data vs. Information

Where is the Life we have lost in living?

Where is the wisdom we have lost in knowledge?

Where is the knowledge we have lost in information?

T. S. Eliot,"The Rock", Faber & Faber 1934.

1


Data Representation – DIKW

Distinction between:Data—raw, unformatted information

Example: 5433333353

Information—data that is transformed to have a meaning

Example: (543) 333-3353

Knowledge—body of governing procedures used to organize or manipulate dataWisdom—accumulated knowledge

1


DIKW Pyramid

1 Data vs. Information Data: 51007 Information:

– 5/10/07 The date of your final exam.– $51,007 The average starting salary of an

accounting major.– 51007 Zip code of Bronson Iowa.

1

Data 6.34 6.45 6.39 6.62 6.57 6.64 6.71 6.82 7.12 7.06

SIRIUS SATELLITE RADIO INC.

$5.80

$6.00

$6.20

$6.40

$6.60

$6.80

$7.00

$7.20

1 2 3 4 5 6 7 8 9 10

Last 10 Days

Sto

ck P

rice

Information

Data vs. Information

1 Data Information Knowledge

Data

Information

Summarizing the data

Averaging the data

Selecting part of the data

Graphing the data

Adding context

Adding value

1 Data Information Knowledge

Information

Knowledge

How is the info tied to outcomes?

Are there any patterns in the info?

What info is relevant to the problem?

How does this info effect the system?

What is the best way to use the info?

How can we add more value to the info?

1 What is an analog signal?Most of the signals sensed by humans are analog signals. Everyday examples include sound, light and temperature.

An analog signal may have any value within a continuous range.

An analog signal can be converted into an electrical signal. This graph shows how the voltage of an analog signal varies with time.

time

volt

age

1 What is a digital signal?Modern communication systems carry information from analog signals as digital signals, which have two values: ‘0’ (off) and ‘1’ (on). These are used to encode analog information.

Unlike analog, a digital signal does not vary smoothly, and so is described as being a discontinuous signal.

Digital signals can be sent as electrical signals, radio waves or as pulses of light through optical fibers.

time

curr

ent

1 Digital Media The process of taking analog data, such as a

human voice, and turning it into a data file on a disk is called digitizing.

Digital media collectively refers to digital copies of any form of media.

The main advantage of digital media vs. analog data is that it can be reproduced an infinite number of times with no degradation of quality.

1


Data Representation Data representation refers to the form in which

data is stored, processed, and transmitted Digital devices work with distinct and separate

data (discrete, on/off) using electronic switches Analog devices work with continuous data

Which is which?

1


Representing, Storing, and Processing Multimedia

Numeric & Character data– Binary number system– ASCII, Extended ASCII,

EBCDIC, and Unicode

Bit = Binary Digit – on or off, 1 or 0

Media: texts, sounds, images, videos,..

What is Binary_BrainPop

1


Data Representation

Extended ASCII (total 256 8-bit representation of each character)

American Standard Code for Information Interchange

1

11-15

Place Value in a Binary Number

Binary works the same way except that the place values are successive powers of 2

powers of 2powers of 10

1

11-16


Given binary representation, we can find the decimal equivalent value by multiplying the digit times the place value and adding the results

Decimal Binary

Place value

Place value

1

11-17


Given binary representation, we can find the decimal equivalent value by multiplying the digit times the place value and adding the results

1 Question - 1 1. How do digital machines use and store data?

A. With words

B. With binary numbers

C. With long, drawn out stories

D. With symbols


1 Question - 2 2. What two symbols are generally used in

binary code?A. x and y

B. Upside-down and right-side-up

C. 0 and 1

D. Left side-down and right-side-up


1 Question - 3 3. Humans do math using a base-10 system,

while computers do math using ?A. A base-3 system

B. A base-2 system

C. A base-1 system


1 Question - 4 4. How would you write the number two in

binary?A. 1001

B. 0000

C. 0010

D. 0001


1 Question - 5 5. How high can you count in binary?

A. As high as you want

B. Up to 2

C. Up to 10

D. Up to 1 million


1 Question - 6 6. What type of test is most similar to binary?

A. Writing an essay

B. Fill-in-the-blank

C. Multiple choice

D. True or false


1 Question - 7 7. Your computer's code for the letter A is

01000001. Can you guess what the letter B would be?A. 10010000

B. 01010110

C. 01000010


1 Question - 8 8. Why do humans use a base-10 numerical

system?A. Because 10 is a round number

B. Because we have 10 fingers and 10 toes

C. Because there are 10 planets


1 Question - 9 9. Which of the following devices uses binary

code?


A C DB

1 Question - 10 10. What is the main function of binary code?

A. Turning switches on and off

B. Allowing computers to represent and store data

C. Providing a gateway into higher mathematics

D. Allowing computers to interact with humans


1 Bits and bytes Bits are rarely seen alone in computers. They are

almost always bundled together into 8-bit collections, and these collections are called bytes.

With 8 bits in a byte, you can represent 256 values ranging from 0 to 255, as shown here:

0 = 00000000 1 = 00000001 2 = 00000010

...

254 = 11111110255 = 11111111

1


Data Representation

Extended ASCII (total 256 8-bit representation of each character)

American Standard Code for Information Interchange

1Number of possible values = 2(number of bits)

More bits can encode more information.

More bits require more computer storage.

We want to keep the list small enough to use fewer bits, but we don't want to leave out critical characters

1 Quick Quiz

How many bits are there in a byte?A. 2.

B. 4.

C. 6.

D. 8.

1 Quick Quiz

When you shop for digital devices, their capabilities are often touted in terms of speed and capacity.

Suppose you’re shopping for a USB Flash drive.

A friend recommends one that’s 64 GB. What does

that mean?A. It operates at 64 gigabits per second.

B. It holds 64 billion bytes of data.

C. It holds 64 million 0s and 1s to represent data.

D. It uses 64-bit ASCII code to hold data.

1 Section A: Digital Sound Digital Audio Basics Digital Audio File Formats MIDI Music Speech Recognition and Synthesis

Chapter 8: Digital Media 34

1 Bridging Analog and Digital

We need a sound card that contains

Analog-to-Digital Converter (ADC)

Digital-to-Analog Converter (DAC)

CPU-DSP

1 Digital Audio Basics Sampling a sound wave

– Amplitude of each the sound is stored as a binary number


1 Digital Audio Basics Sampling rate refers to number of

times per second that a sound is measured during the recording process. In other words, how often you take a data.


1 Digital Audio Basics Sampling Rate (vertical slice)


In the image above, the left half has a low sample rate, and the right half has a high sample rate (i.e., high resolution).

Low sample rate High sample rate

1 Digital Audio Basics Sampling Format (Dynamic Range, Bit Depth)


Usually measured by the number of computer bits used to represent each sample. The more bits that are used, the more precise the representation of each sample.

Bit depth refers to the number of allowable levels you map (or round) the values to.

Increasing the number of bits also increases the maximum dynamic range of the audio recording, in other words the difference in volume between the loudest and softest possible sounds that can be represented.

1 Digital Audio Basics Sampling Format (horizontal slice)


In the image above, the left half has a sample format with few bits, and the right half has a sample format with more bits.

Fewer Bits More Bits

1 Sampling Factors

Number of Measurements for Per Second

Numberof

Steps

Sampling Rate

Sampling Size (precision)

http://www.scribd.com/doc/10732516/introduction-to-digital-technology; http://electronics.howstuffworks.com/analog-digital3.htm

1 Examples

Better Quality

http://www.scribd.com/doc/10732516/introduction-to-digital-technology; http://electronics.howstuffworks.com/analog-digital3.htm

Increasing sampling rate and size

1 Bits and bytes in Audio

CD uses 2 bytes, or 16 bits, per sample per channel. That gives each sample a range from 0 to 65,535, like this:

0 = 0000000000000000 1 = 0000000000000001 2 = 0000000000000010

...65534 = 111111111111111065535 = 1111111111111111

216 = 65536

1 Digital Audio File Formats The most popular digital audio formats

include WAV (Uncompressed, de facto standard for sound on PCs), and lossy formats including AAC, MP3, Ogg Vorbis (free), and WMA (Windows Media Audio)

Audio or media player software allows you to play digital audio files

You can embed digital audio files into a Web page using the HTML5 <audio> tag


Introduction to digital sound

1 CD Storage Capacity Without compression, a CD can store up to 74-

minutes (650 Megabytes) of music.

With compression, in forms like MP3, about 10 times as many minutes can be stored in a CD-R.

1 What is Streaming? Process of delivering audio, video and other

multimedia over a network The network could be a LAN, Intranet or Internet for

example Streaming ensures no download wait No files to take up space on your hard disk. It could be audio or video streaming It is getting more popular as broadband access

becomes widespread

1 Section B: Bitmap Graphics Bitmap Basics Scanners and Cameras Image Resolution Color Depth and Palettes Image Compression


1 Digital Image Basics


You can capture images using certain devices connected to the computer, such as a digital camera, scanner, or screenshot of the display.

You can also create images on the computer using painting and drawing programs and using a mouse, a digital pen or stylus.

1 Scanners and Cameras


1 Scanners and Cameras


The CCD (Charge Coupled Device) is an image sensor and the camera’s “film.” It captures the light falling on it and convert it into electrical signals. The CCD surface is divided like a grid, into small pixels. Each pixel represents one pixel in the captured image.

Area CCD Line CCD

1 CCD


The CCD (Charge Coupled Device) is an image sensor made of semiconductor – the same kind of materials as computer chips – to capture light and turn it into an electric signal.

The inventors, Willard Boyle and George E. Smith, were awarded the 2009 Nobel Prize in physics.

1All captured images are called bitmap images.

If you take a close look you will see that an image is made up of pixels.

Pixels (short for picture elements) are the small sections of color and/or tone that together form a digital image.

Pixels

1 Bitmap/Raster Graphics Basics

Composed of a grid of dots/pixels– Color of each dot/pixel is stored as a binary number

(commonly 24 bits)


You use your smartphone to take a photo. Which camera – front or back – gives you a better quality photo?

1 Bits and Bytes in Graphics

A pixel in an image file is a piece of data. It is the smallest unit of picture that can be represented or controlled.

Similar to sound, each pixel is a sample of an original image; more samples typically provide more accurate representations of the original.

It could be represented in 1 bit, 1 byte, or 3 bytes How many colors can you represent if a pixel is

1 bit: 21 = 2 colors (monochrome)1 byte: 28 = 256 colors (GIF file)3 bytes: 224 = ~16 million colors ("Truecolor")

True Color bitmap (24-bit=3×8-bit channels (RGB))

1 Bitmap Formats for Photo


BMP

RAW

TIFF

1 Bitmap Formats for Web


GIF

JPG

PNG

1 Image Resolution (Bitmap) Expressed as the number of horizontal and vertical

pixels, for instance “1520 (width) x 1280 (height)”.– Higher resolutions contain more data (larger file size) and

are higher quality

Bitmaps do not have a fixed physical size


1

The ppi of the image is called the resolution.

An image with lots of ppi is a high resolution image and vice versa.

Bitmap images are resolution dependent; meaning that if you scale up a bitmap, the pixels will become more visible and the quality of the graphic compromised.

Bitmap images are measured in pixels per inch, otherwise known as ppi.

Higher or Lower Resolution

1 Higher or Lower Resolution

For a given image, the higher the ppi, the better quality (more details) the image.

Which one looks more like a circle?

1 Image Resolution (Bitmap)


Image Resolution (“ppi”): as the pixel count per inch drops, the individual pixels will begin to show, and the image will appear "pixelated" (jagged, blurry, and/or chunky), as shown in the example pictures above. A high resolution image will still be clear when scaled up.

1 Image Resolution (Bitmap)


300 ppi 72 ppi 10 ppi300 ppi

Simulated image resolution (ppi) examples

magazine web standard

Desktop monitors pixel density have exceeded 200 ppi and contemporary small-screen mobile devices often exceed 300 ppi to over 400ppi (1080p) for some smartphones.

1 Bitmap Basics – Color Depth A bitmap image is a collection of color dots called

pixels, arranged in rows and columns. A pixel is the smallest picture element that can be

shown on a display. The number of colors can be displayed in a pixel is

determined by the number of bits used to represent the pixel (know as color depth).

The larger the color depth, the larger the number of colors can be displayed.


Remember bit depth for sound?

1 Color Depth and Palettes Color depth is the number of colors available for

use in an image– Monochrome bitmap

Increasing color depth increases file size Color palettes are used to control color depth

– Grayscale palette– System palette– Web palette


1

The systems that are used to create websites, usually have a video card capable of displaying 64 thousand (16-bit) or 16.7 millions (24-bit) colors.

The average visitor of a website is capable of viewing web-safe 256 (=28) colors (8-bit).

Nowadays most computer monitors can display 16-bit or more colors.

Color – On the Computer & Internet

1

81

Color Value Color Color HEX Color RGB

#000000 rgb(0,0,0)

#FF0000 rgb(255,0,0)

#00FF00 rgb(0,255,0)

#0000FF rgb(0,0,255)

#FFFF00 rgb(255,255,0)

#00FFFF rgb(0,255,255)

#FF00FF rgb(255,0,255)

#C0C0C0 rgb(192,192,192)

#FFFFFF rgb(255,255,255)

The lowest value that can be given to one of the light sources is 0 (hex 00). The highest value is 255 (hex FF).

RG

B

Gray

GrayGray

1

82

Color Value

1 Section C: Vector and 3-D Graphics

Vector Graphics Basics Vector-to-Bitmap Conversion Vector Graphics on the Web 3-D Graphics


Vector VS Bitmap

1The other type of images are vector images. These images are created in special drawing programs.

Vector images are made up of lines and shapes. These can be grouped together to make up another shape.

When images are made bigger the quality remains the same.

Vector Graphic Basics

1 Vector Graphic Basics Contain instructions (mathematical formula) for

re-creating a picture


SVG (Scalable Vector Graphics) and Flash are two vector graphics formats that can be used on the Web

Most fonts font formats are based on vectors.

WMF (Windows MetaFile) files can contain both vector and bitmap. image. information.

1 Vector Graphic Basics Vector graphics resize better than bitmaps Vector graphics are resolution independent Vector graphics usually require less storage space

than bitmaps Vector graphics are not usually as realistic as

bitmap images It is easier to edit an object in a vector graphic than

an object in a bitmap graphic


1

Bitmapped or raster fonts

Vector fonts

TrueType, OpenType, PostScript

Courier, MS Sans Serif, MS Serif, Small, Symbol

1 3-D Graphics Stored as a set of instructions

– Contain locations and lengths of lines forming a wireframe

Rendering covers a wireframe with surface color and texture, which makes 3-D vectors look more realistic

Ray tracing adds light and shadows to a 3-D image to simulate the eye's perception of those objects


1 3-D Graphics – Wireframe


1 3-D Graphics – Modeling


Simple 3D objects can be modeled using mathematical equations operating in the 3-dimensional Cartesian coordinate system.

Example:

the equation x2 + y2 + z2 = r2

is a model of a perfect sphere with radius r.

1 3-D Graphics – Rendering


The process of taking the mathematical model of the world and producing the output image.

The core of the rendering process involves projecting the 3D models onto a 2D image plane.

1 3-D Graphics – Rendering


1 Bitmap vs. Vector Graphics


Bitmap images are, with a few exceptions, the standard for internet graphics, as well as Windows icons and backgrounds. Bitmaps are also the standard format for images captured by scanners and digital cameras.

Rather than being comprised of pixels, the vector image is made up of various “objects,” a term which essentially means lines and shapes.

Photo-Realism, Scalability, Shape, File Size are some factors to consider to choose one over the other.

1 Question 082300 2-D vectors don’t look very realistic, whereas

3-D vectors tend to look very realistic. Why is this the case?– A. 3-D images use a more realistic color palette than 2-D

images.– B. 3-D images constructed using a wireframe can be

rendered with surface textures and lighted with realistic ray tracing.

– C. 3-D images can be enlarged or shrunk more realistically than 2-D images.

– D. 3-D images can be animated, whereas 2-D images cannot.


1 Section D: Digital Video Digital Video Basics Producing Video Footage Video Transfer Video Editing Video Output Web Video DVD-Video


1 Digital Video Basics Uses bits to store color and brightness

data for each video frame The color for each pixel is represented

by a binary number Footage for digital videos can be

supplied from a digital source, or from an analog source that requires conversion


1 Digital Video Basics Bitrate – the amount of data (bits) used

to encode video or audio Frame rate (FPS) – also known as

frame frequency, is the frequency (rate) at which an imaging device displays consecutive images called frames. The higher the frame rate, the better the optical illusion.

24 fps is the standard for film and 30 and 25 fps is for TV based on NTSC and PAL, respectively.


1 Video Output


In general, a higher bitrate will accommodate higher image quality in the video output.

1 Question 082400 YouTube is a popular video site. Which one

of the following statements is NOT true about these videos?– A. YouTube supports streaming video.– B. Users can flag content they feel is

inappropriate.– C. YouTube videos have a low compression

ratio and a high bitrate.– D. Each YouTube video has a unique URL.


1 Image Compression


1 Strategies to Reduce Digital Media File Size

Reduce the sampling rate Reduce the bit depth Apply file compression

1 1. Reduce Sampling Rate

Recall the weighing puppy scenario If you weigh the puppy more frequently, it will

take more paper.

For digital media files, higher sampling rate means more data to store.

In other words, lower sample rate will produce less data, i.e. smaller file size.

1 2. Reduce Bit Depth Bit depth refers to the number of allowable

levels you can map the data

For digital media files, lower bit depth means less data to store.

1 3. Compression Efficient Storage (small file size) Streaming Interactive Multimedia Applications

Two categories in terms of whether the data get lost during the compression:– lossy compression– lossless compression

1 Compression Goals Reduced bandwidth Make decoded signal sound as close as

possible to original signal Lowest Implementation Complexity Robust Scalable

1 Audio Compression

Removing bits that represent extraneous noise

Removing sounds that are beyond the frequencies of normal hearing

1 Lossy Compression

Some data will be lost and cannot be recovered

Examples:– JPEG compression for images– MP3 for audio– most compressors for videos

1 Lossy Compression A lossy codec is one that discards certain

portions of the signal in order to achieve a smaller file size without resulting in a perceived loss of quality of the sound to make the file smaller.

Avoid using lossy compression (if possible) when you want to keep the file for further editing.

Video files are generally so large that it is inevitable to save them with lossy compression.

1 Lossless Compression

A lossless codec is one that achieves smaller file sizes through means other than removing data.

This can include using a variable bit rate which would use fewer bits to encode silences as compared to an active section of music.

1 Image Compression Any technique that recodes data in an image file so

that it contains fewer bits– Lossless compression– Lossy compression

Run-length encoding File compression utility


1 Image Compression


1

File formats come in two types: lossy and lossless.

Lossy formats lose some of the image colours when the file is saved (those not usually seen by the naked eye!).While the quality of the image may not be the best possible, lossy formats are useful as they do not take up a lot of memory.

Lossless formats save the image as it is – this ensures that the quality remains the same. However, they take up more memory than a lossy format.

At a loss?

1File Quality Memory

usedBenefits

.tiff lossless high Very good quality images.

Ideal for printing.

.bmp lossless high Very good quality images.

Ideal for printing.

.gif lossless low Used for images with less than 256 colours. Ideal for animations, text and line drawings, and web site animations.

Has transparency feature.

.jpeg lossy low Good images with up to 16 million colours. Not first choice for printing.

Very good for web site photographs.

.png lossless Very low Images of any quality, printed or not.

Very good for images on a web site.

1 Trade-offs of Reducing File Size

Data will be lost or altered when you apply these strategies:– reduce sampling rate– reduce bit depth– apply lossy compression

When data is lost or altered, you sacrifice the exactness of the media original information. This affects the quality of the media.

1 Weighing the Trade-offs

Depend on projects and intended use of the files

Weigh the file size (storage requirement and speed of transfer and processing of the file) against the quality of the digital media files

Losing data vs. "perceivable" quality – Sometimes it may be acceptable if losing data

does not cause "perceivable" deterioration in quality

1 Question 082200 Bitmap files are typically quite large and so it is

handy to compress them before FTPing or e-mailing them. However, some bitmap files don’t seem to shrink very much when you use a compression utility, such as WinZip. Why?– A. The files are already as small as they can get.– B. Compression utilities use lossless compression, which

won’t allow you shrink the size of a file without losing data.

– C. Some types of files are already in compressed format, which can’t be further compressed.

– D. The files have a small color palette that doesn’t allow compression.


1 FastPoll True/False QuestionsAnswer A for True and B for False

080100 Audio is digitized by dividing a sound wave into samples and storing the numbers that represent the height of each sample.

080200 A higher sampling rate produces higher quality sound than lower sampling rates.

080300 MP3 and BMP are examples of two popular digital music formats.

080400 WAV is a format for synthesized sound. 080500 Software with speech synthesis capabilities can

convert your spoken dictation into a digital document.



080600 RAW, PNG, TIFF, and JPEG formats store graphics as bitmaps.

080700 Bitmap graphics are resolution dependent. 080800 When bitmaps are enlarged, pixel interpolation can

result in the graphic becoming pixilated. 080900 Images that have been compressed with lossless

compression can be reconstituted to their original appearance without any data loss.

081000 Vector graphics maintain their quality better than bitmaps when resized.



081100 The technique for adding light and shadows to a 3-D graphic is called rasterizing.

081200 Videos with a low compression rate tend to be small, low-quality files.

081300 A video with a bitrate of 340 will have less compression and better quality than a video with a bitrate of 150.

081400 Recording a television show to watch at a later time is an example of digital rights management.

081500 Digital watermarks, HDCP, and broadcast flags rely on compliant hardware devices to protect content.


Documents

1 SECTION C Chapter 1: Computers and Digital Basics 1 Digital Data Representation Data Representation Basics Representing Numbers, Text, and Pictures