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  1. DIGITAL TECHNOLOGIES 010011110111010101110100011011000110100101101110011001010010000001101111011001100010000001001011011001010111100100100000010000110110111101101110011000110110010101110000

  2. Digital Technologies 0100111101110101011101000110110001101001011011100110010100100000011011110110011000100000010010110110010101111001001000000100001101101111011011100110001101100101011100000111010001110011 (Outline of Key Concepts)

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  7. Digital Technologies ANALOG processes information in a continuous stream. This can be seen in a clock. An analog clock is one with hands that move around the clock continuously producing a stream of time. Any minute and any fraction of a minute can be represented. For instance, you could look at an analog clock and say with some degree of accuracy that it is one and one half minutes past one o'clock. You could see that the minute hand was half way between one and two minutes. Digital clocks show the time a little differently – usually flashing only the hour and the minute. Analog Signals Analog signals are continuous electrical signals that vary in time. The variations usually follow the non-electric (original) signal. The two are analogous (same), hence the name analog. Analog Signal Analog signals are not always like this wave. They simply ‘MODEL’ a real quantity. A telephone voice signal is analog. The intensity of the voice causes electric current variations. At the receiving end, the signal is reproduced in the same proportion. Hence the electric current is a ‘MODEL’, or analog of a voice.

  8. Digital Technologies DIGITAL describes any system based on discontinuous (which means not continuous or having breaks) data or events. Digital is the opposite of analog.  Digital Signals - are non-continuous, they change in individual steps. They consist of pulses or digits with discrete levels or values. The value of each pulse is constant, but there is an abrupt change from one digit to the next. Digital signals have two amplitude levels called nodes. The value of which are specified as one of two possibilities such as 1 or 0, HIGH or LOW, TRUE or FALSE and so on. Digital vs Analog We experience the world analogically. Vision is an analog experience because we perceive infinitely smooth gradations of shapes and colors. Most analog events, such as vision, however, can be simulated digitally. Photographs consist of an array of dots that are either black or white. From afar, the viewer does not see the dots (the digital form), but only lines and shading, which appear to be continuous. Computers are digital because they distinguish between two values, 0 and 1, or off and on. All data that a computer processes is encoded digitally, as a series of zeroes and ones. Digital Technologies - give us an accurate way to represent data and an easy way to mechanically store and manipulate that data. Digital recordings do not degrade over time and the digital information can be compressed. Converting images or information that we perceive, from analog to digital, and back to analog is possible but is a fine art.

  9. Digital Technologies Digital ImageA digital image is a representation of a two-dimensional image with a set of digital values, called picture elements, or pixels. Pixels are the smallest individual element in an image, holding quantized values that represent the brightness of a given colour at any specific point. Each small pixel is assigned a place and is represented by a number. This long series of numbers can then be stored in the memory of a computer to be accessed at a later time. These values are often transmitted or stored in a compressed form. The digital image contains a fixed number of rows and columns of pixels. Just as in a stadium image (a big picture made out of small colored squares), a digital image is a picture made up of smaller colored pixels. Digital images can be created by devices and techniques, such as digital cameras, scanners, coordinate-measuring machines, seismographic profiling, airborne radar, and more. Digital Image processing is the study of algorithms that reproduce images. Digital Signal Processing (DSP) is a field that is concerned with manipulating signals in digital form. Manipulating signals in digital form has many advantages over manipulating signals in analogue form.The signal must go through a process of conversion from analogue to digital. Then it is compressed so that it can be transmitted efficiently. At the receiver end the original voice signal is recovered.

  10. Digital Technologies Coloring A Digital image Once the individual pixels are in the correct order, each pixel is assigned a value, which corresponds to a specific color. When the picture gets reassembled, the computer reads the value of each pixel and makes that pixel the correct color. Digital Image Quality (Resolution) The quality of the digital image depends on the size of the pixels. If the pixel is large you will see the image as a collection of small squares. If the pixel is small you will not notice the squares. The quality of the image is called its resolution. The more pixels in the image, the higher the resolution. Resolution is sometimes identified by the width and height of the image as well as the total number of pixels in the image. An image 2048 pixels wide by 1536 pixels high (2048X1536) equals (multiply) 3,145,728 pixels (or 3.1 Megapixels).  Therefore a 5 megapixel camera is capable of capturing a higher resolution image than a 3 megapixel camera. Image quality and image size determine the number of photographs that can be stored on a memory card. The FINE mode provides sharper images than the NORMAL mode, which is in turn has better image quality than the BASIC mode. The loss-of-quality is mainly due to enlargement. Therefore, the image quality should still be very good, even in high compression modes, as long as the image is not enlarged. If image quality is critical, use the FINE mode.

  11. Digital Technologies This is why you'll get better prints from a 3 megapixel camera when compared to a 2 megapixel camera. More resolution means better quality - up to a point. Both optics and the quality of the image capture chip play a role too. At their actual size even the smallest of them would likely be larger than your entire computer screen. Notice the tremendous difference between 2.1 megapixels and 3.3 megapixels.

  12. Digital Technologies Higher Resolution Advantage In general more resolution means better print quality. The advantage of having a camera with a higher resolution is you have more pixels to work with. That's important when getting prints made. A print can be made from just about any image, but the more you have to blow it up, the more you degrade the quality. Starting with a higher resolution image means there's less magnification necessary to get to a given print size. It also gives you an advantage if you need to crop the image. Cropping is when you only use part of the image for the final print. It also gives you an advantage when creating larger 5x7, 8x10, or bigger prints. The more you have to blow an image up the more any defects will start to jump out.

  13. Digital Technologies • Information Storage • There are many different methods and technologies used to store digital images. Most fall into one of three categories, depending on how they actually record (write) the image data.  The three types are: • Electronic • Magnetic • Optical • Most information today is stored digitally (converted into numbers). • JPEG is arguably the most loved file format on the planet.  Everyone loves the amazing compression they gain by using it.  Camera manufacturers love the fact that the resulting smaller images can be quickly written to digital film and later transferred to your computer easily.  • JPEG is also the most hated file format, because it brings with it distortion - an image compressed using JPEG will never be identical to the original image.  And each time we recompress it, it gets a little worse.  • Except in some very rare cases where you are only capturing images where you'll only ever need small versions for use on the web, stay away from all but the highest quality JPEG compressions settings on your camera.  After all, once you've captured the image you can't go back and add more detail, but you can always compress it more later.

  14. Digital Technologies Archival Storage This is about making sure that you have readable images in the future. The first challenge is what medium to use to record the images.  There are some options. CD-RW and CD-R The most discussed and possibly most common image backup system is some form of CD. CD writers are common and inexpensive and CD-R disks can keep over 600MB at under $1 per disk. If you take a lot of pictures, saving high quality images will require a lot of CDs! The life of the CD is only as good as the equipment you use - to write it on and read it on.  For the safest archival storage you're best off writing the entire CD at once, verifying it, and then storing it properly. DVD-RAM and DVD Writers (DVD has more memory capacity than a CD) DVD-RAM, although not true DVD, because it can't be played in a regular DVD player, do hold 5.2GB per cartridge and are re-writable.  The DVD-RAM cartridges are expensive and the software drivers for DVD-RAM can be a pain to get configured. DVD writers have a 5+GB per disk capacity - making them a no-brainer as the current solution to the proliferation of CDs! 

  15. Digital Technologies Tape Cartridges Tape cartridges are very effective alternatives for disaster-recovery storage.  Because they are not direct access media it can take minutes to find a particular image-so they are not very useful as a working library-but their capacity of 20GB and up makes them ideal as a backup system.  Since JPEG images are already compressed you'll only get the lower or "un-compressed" capacity of your backup tapes-as the backup system won't be able to compress your images any further.  Off-site Storage Keeping a duplicate copy of your entire image library in a safe deposit box at your bank-or somewhere else safe and offsite-is an excellent precaution.  One easy way to do this is every quarter when you make your permanent backup tapes take your last set down to the bank.  Tapes can go bad so you're best off to keep a few sets there in case one of them develops a problem. Internet Backup There are many image and digital information backup services available on the Internet.   Having your own back-up space is the best answer, but if you don’t have the devices or digital resources, Internet services may be an option for storing your data.

  16. Digital Technologies Optical Media in several different forms can be used to store and archive large quantities of images.  Most medical digital image systems use a combination of storage and memory devices.  The function of each depends on it's capabilities and it's limitations. Compact Disk (CD) One of the most widely used optical storage forms uses light to record data. The bit positions are located along a long spiral path running from the outer edge to near the center of the disk.  The surface of the disk is material that reflects light. Writing or recording is done by a laser.  This laser produces a relatively intense beam of light that is directed to the bit positions as the disk rotates.  The laser beam is turned on and off by the series of pulses representing the bits to be recorded.  If the beam is off as it passes over a bit position, the reflective surface is not affected, and that bit position remains as a "little mirror" that will reflect light.  If the laser beam is on as it passes over a bit position, it "burns" the surface and destroys the ability to reflect.  With this process each bit position is now marked by being either reflecting or nonreflecting. When the bit positions pass under the read laser (which is less intense than the write laser) they either reflect or do not reflect the light to a detector that converts the light pulses into electrical pulses.  CDs, have a relatively large storage capacity because the optical recording process can form very small bits on the surface of the disk. However, a major advantage is that most optical recording media, such as CDs, are on disk that are easily exchangeable.

  17. Digital Technologies • Information Retrieval • All digital imaging systems have one or more components (media) in or on which the digital images are stored - "Storage Media". • Characteristics of storage media include: • Capacity (Number of images that can be stored) • Speed (Time required to write/record and read/retrieve images) • Reliability and Security (To prevent loss of images) • All computers and digital imaging systems have some form of electronic storage that is usually referred to as "memory". This form of storage or memory consist of an array of many electronic components (like transistors) that can be "set" to remember bits. • Random Access Memory (usually called RAM) allows data to be written/recorded and read/retrieved to and from any place within the memory array ( random access) of the computing device you are using. This is to distinguish it from a storage device, like tape, where the data is stored and retrieved in sequence. General characteristics of RAM include: • Fast writing/recording and reading. • Relatively limited capacity in comparison to the other storage media. • Requires electrical power to maintain the stored data. • The RAM is used to store images and other data short term.

  18. Digital Technologies • Transmitting Digital Images • Digital images can be sent over vast distances, without having to be processed. A powerful computer can convert the digital information very quickly. Digital imaging can also collect different parts of the electromagnetic spectrum, allowing infrared as well as visible images to be captured. • Wireless Technologies • Wireless normally refers to any type of electrical or electronic operation which is accomplished without the use of a "hard wired" connection. Wireless communication is the transfer of information over a distance without the use of electrical conductors or "wires".[ Wireless technologies represent a rapidly emerging area of growth and importance for providing access to information. Wireless is used in many applications: connecting computers, allowing remote monitoring and data acquisition, providing access control and security, and providing a solution for environments where wires may not be available. • Common applications of wireless technologies include: • Voice and text messaging • Hand-held and other Internet-enabled devices • Data Networking • Wireless communications is generally considered to be a branch of telecommunications, which includes cellular telephones, personal digital assistants (PDAs), GPS units, garage door openers, wireless computer mice, keyboards, satellite television, cordless telephones and wireless networking.

  19. Digital Technologies Voice and Text Messaging Cell phones, pagers, and commercial two-way business radios provide voice and text messaging services. These devices operate within networks that provide local or widespread coverage. These large and costly networks are operated by carriers such as AT&T, Sprint, Verizon, Bell, Telus, etc. and operate in different frequency bands which are assigned by the governing authority. Hand-held and Internet-enabled devices Internet-enabled cell phones and Personal Digital Assistants (PDAs) have emerged as the newest products that can connect to the Internet across a digital wireless network. New protocols, such as Wireless Application Protocol (WAP), and new languages, such as WML (Wireless Markup Language) have been developed specifically for these devices to connect to the Internet. However, the majority of current Internet content is not totally optimized for these devices. Data Networking We differentiate between pure data applications in wireless local area networks (WLANs) and data, voice, and video converged in broadband wireless. Wireless Local Area Networks Wireless Local Area Networks (WLAN) are implemented as an extension to wired LANs within a building and can provide the final few meters of connectivity between a wired network and the mobile user.

  20. Digital Technologies Broadband Wireless Broadband wireless is a wireless technology that allows simultaneous wireless delivery of voice, data, and video. Broadband is a competing technology with Digital Subscriber Line (DSL). It is generally implemented in metropolitan areas and requires clear line of sight between the transmitter and the receiving end. Bluetooth Bluetooth is a technology specification for small form factor, low-cost, short-range wireless links between mobile PCs, mobile phones, and other portable handheld devices, and connectivity to the Internet. Security Data security is an issue for wireless technologies due to the nature of the transmission mechanism (electromagnetic signals passing through the air). Voice applications are less secure than data applications, due to limited capabilities of existing technologies to protect information that is being transmitted.

  21. Digital Technologies The Internet is a worldwide, publicly accessible series of interconnected computer networks that transmit data by packet switching using the standard Internet Protocol (IP). It is a "network of networks" that consists of millions of smaller domestic, academic, business, and government networks, which together carry various information and services, such as email, chat, file transfer, and the interlinked web pages and other resources of the World Wide Web (WWW). Aside from the complex physical connections that make up its infrastructure, the Internet is facilitated by bi- or multi-lateral commercial contracts (e.g., peering agreements), and by technical specifications or protocols that describe how to exchange data over the network. The Internet is fast becoming a basic feature of global civilization, so that what has traditionally been called "civil society" is now becoming identical with information technology society as defined by Internet use. Only 2% of the World's population regularly accesses the internet. World Wide Web The World Wide Web is a huge set of interlinked documents, images and other resources, linked by hyperlinks and URLs. These hyperlinks and URLs allow the web-servers and other machines that store originals, and cached copies, of these resources to deliver them as required using HTTP (Hypertext Transfer Protocol). HTTP is only one of the communication protocols used on the Internet. The World Wide Web is one of the services accessible using the Internet, along with many others including e-mail, Usenet, file sharing and others.