GIF (Graphic Interchange Format)

GIF uses LZW lossless compression. Each pixel is represented in 8 bits, which allows for 256 colours. It makes image file size  of 3.85 Mb to 886 Kb. Although it makes file smaller size but the image become jerkyer than actual one.

IMAGE(G)

JPEG (Joint Photographic Expert Group)

This file format uses lossy compression which means loss quality of the image.  It makes image file size  of 3.85 Mb to 758 Kb. Although it makes file smaller size but the image has lost some of quality.

IMAGE(J)

PNG(Portable Network Graphic)

This is a lossless file format. The PNG file format has a higher compression factor than GIF files. The file size bigger than JEPG and GIF since it has more features than other format.

IMAGE(P)

Comparing  Wi-Fi vs Bluetooth

Bluetooth technology is useful when transferring information between two or more devices that are near each other when speed is not an issue, such as telephones, printers, modems and headsets whereas Wi-Fi is better suited for operating full-scale networks because it enables a faster connection, better range from the base station.

Wi-fi has better security than Bluetooth. Bluetooth is cheaper than Wi-fi.

Finaly, Bluetooth can transfer data up to 2.1 MB per Second whereas Wi-fi can transfer data up to 600 MB per second.

Bluetooth is mostly used by device such as Mobile phones, mouse, keyboards, office and industrial automation devices whereas Wi-fi is used by device such as Notebook computers, desktop computers, servers, TV, Latest mobiles.

Comparing Firewire vs USB

Firewire

Firewire Plug and LogoFireWire is Apple’s name for their high speed interface standard previously known as IEEE-1394. The intention to develop FireWire was to provide a replacement for the parallel SCSI bus while also providing connectivity for digital audio and video equipment. FireWire allows multiple devices to be connected to a single adapter with blistering speed.

The earlier FireWire 400 standard is capable of transferring data between devices up to 400 Mbit/s, and allows up to 63 devices connecting simultaneously on a single controller. Additionally, the “Peer-to-Peer” architecture of FireWire also makes it possible for devices to communicate without the need of a CPU.

FireWire 800 (or IEEE 1394b) improves the previous FireWire data transfer rate up to 800 Mbit/s.

USB

USB Plug and LogoUSB stands for Universal Serial Bus. It was designed primarily to replace serial and parallel ports on personal computers to eliminate the need of developing separate device drivers.

USB also allows multiple (up to 127) devices to be daisy-chained together in a single USB port using additional USB hubs, but unlike FireWire, USB needs the presence of a CPU to control the bus and the data transfer, making it less versatile compared to FireWire.

The first generation of USB has a data transfer rate up to 12Mb/s, while the later USB 2.0 standard allows up to 480 Mb/s data transfer rate.

Magnetic Storage

One of the common aspects of modern computer hardware is a technology known as a magnetic storage device. This is a technology available in multiple forms, such as a floppy disk drive, a tape drive and a hard drive. The most popular one is hard drive. It can hold out at least a terabyte of information both internal and externally which is as enough different music to listen to while working a full-time job for an entire year. On the other hand floppy held 1.44 megabytes (MB) of data, or roughly 750 text-only pages (750 pages is about a ream and a half of paper).

 

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Vector Graphic

Posted: April 10, 2013 in Uncategorized

Unlike Bit mapped graphics, Vector graphics are not made of a grid of pixels. Instead,  Vector graphic stores the image as a list of objects, each object being described by its attributes. 

Examples of Vector Graphics:

       

 

Comparison of Bit-mapped Graphics and Vector Graphics

  •  Bit-mapped graphics can be edited in fine details at the pixel level, but vector graphics are edited by changing the attributes of objects.
  • Bit-mapped graphics have large storage requirements to store all the pixels, but it requires much more less storage for vector graphics to store codes for objects and their attributes.
  •  Bit-mapped graphics are stored at a pixel resolution, but vector graphics are resolution-independent. Therefore vector graphics can take advantage of high resolution output device such as a printer, but bit-mapped graphics can not.
  •  Bit-mapped graphics become jagged when enlarged, but vector graphics do not since the resolution is not fixed.

Dithering is a technique used to soften jagged edges of lines and curves at low resolution by placing
different-coloured pixels in block of colour. Since human eye tends to blur spots of different colours so Dithering tricked human eye by identifying group of dots or pixels that have pattern then merging them into a shade of colour.

Aliasing refers to the jagged appearance of curves or diagonal lines on low resolution display. Anti-aliasing is software technique for smoothing these edges though by changing the shading, size or alignment of some of the pixels.

increased resolution(re-sampled) where a image may be required to be re sampled by rescanning at a higher resolution to give finer details and reduce the jagged appearance of the image.

The Processor

Posted: December 11, 2012 in Uncategorized

The processor is responsible for fetching instructions held in main memory and executing one at a time. The Processor is consists of a Control Unit, Arithmetic logic Unit and Registers.

Control Unit

Control Unit is responsible for the fetching, decoding and execution of instructions by sending out signals to other parts of the computer system

Arithmetic logic Unit

The Arithmetic logic Unit carries out Arithmetic operations and logical operation such as AND, OR, NOT etc.

Registers

Registers are individual storage locations on the processor which hold an instruction, Data or the address of a memory location.

Buses

Buses are used to transfer data and send signals between the processor and main memory. There are different type of buses which are Data bus, Address bus and Control bus.

Address Bus

This bus is used to specify the address of the memory location that to be read from or written to. It is a one-way bus.

Data Bus

This is used to transfer data between main memory and the processor. It is a two-way bus.

Control Bus

Each control bus line has different function. Example of Control buses are Read, Write, Clock, Reset and Interrupt.

Fetch-execute cycle

During the execution of a program, the processor reads data from memory locations and writes data to memory address.

Read Data

A processor reads items of data to perform calculation.

Step 1 The processor sets up the address bus with the address of the required memory location.

Step 2 The processor activates the read line on the control bus.

Step 3 the contents of the memory location are transferred along the data bus into the processor.

Step 4 If it is an instruction, it is decoded and executed.

Write Data

The processor sometimes writes the results of calculations to memory.

Step 1 The processor sets up the address bus with the address of the required memory location.

Step 2 The processor sets up the data bus with the data to be written to memory.

Step 3 The processor activates the Write line on the control bus.

Step 4 The data is transferred along the data bus to the memory location

 

Representing Graphics

Posted: December 4, 2012 in Uncategorized

Bit-mapped Graphics

This type of graphics stores the image as colour codes of pixels. An image made up by lots of tiny dot which is called pixel.

Bit Depth

The number of bits that are used to represent the colour of each pixel is called the bit depth.

An image using 1-bit depth will only be able to represent two colours  – usually black and white.

Resolution  

The resolution is the size of the pixels and usually measured in dots per inch.

Vectors Graphics

This type of graphic stores the image as a list of objects, each object being described by its attributes.

Comparison of Bit-mapped Graphics and Vector Graphics

  •  Bit-mapped graphics can be edited in fine details at the pixel level, but vector graphics are edited by changing the attributes of objects.
  • Bit-mapped graphics have large storage requirements to store all the pixels, but it requires much more less storage for vector graphics to store codes for objects and their attributes.
  •  Bit-mapped graphics are stored at a pixel resolution, but vector graphics are resolution-independent. Therefore vector graphics can take advantage of high resolution output device such as a printer, but bit-mapped graphics can not.
  •  Bit-mapped graphics become jagged when enlarged, but vector graphics do not since the resolution is not fixed.

Standard Algorithm

Posted: October 3, 2012 in Uncategorized

An algorithm is a finite sequence of steps which, when followed, will accomplish a
particular task. Many algorithms appear over and over again, in program after program. These are called standard algorithms or common algorithms. Linear Search, Count Occurrences, Finding Maximum and Finding Minimum those are Standard Algorithm.

Linear Search

Linear Search is searching for an item though a list, comparing each item in the list with searching item. When it finds the searching item it will return the position of searching item. e.g.

16     9     34    76   85  2   25  82  55

Suppose the search key is 76.

1. 16 is compared to 76. Not the key so pointer moves on one place

2. 9 is compared to the key. Not equal so pointer moves on

3. 34 is compared to key. Not equal so pointer moves on

4. 76 compared with key. Success! Key found at position 4 in the list.

16     9     34    76   85  2   25  82  55

In this method program is stopped when searching value is found. This algorithm is shown below:

1. get search_number

2. repeat for all numbers in list

2.1 if current_number = search_number then

2.1.1 position = current_item position

2.1.2 exit loop

2.2 end if

3. end repeat

4. display position

This is how the program works

Count Occurrences 

Count Occurrences counts how often a value occurs in a list.

Algorithm

1. set counter to 0
2. get occurrences_number
2. repeat for all numbers in list

2.1 if current_number = occurrences_number then
2.1.1 counter = counter + 1
2.2 end if

3. end repeat
4. display counter

This is how program is working

Image