COMPUTER GRAPHICS IN BCA 3 YEAR
Computer Graphics
What is Computer Graphics?
Computer graphics is an art in which images, lines, and charts are created by programming them in a computer.
Simply put, "Drawing pictures on a computer screen is called computer graphics."
Creating pictures with the help of a computer is called computer graphics. In this, two or three dimensional pictures are created. It uses a lot of software techniques to create, modify, and store pictures.
With the help of Computer Graphics, we can display images of any size in the computer screen. Graphics are presented in computers using a lot of algorithms and techniques.
Nowadays, computer graphics are used everywhere such as – in user interfaces, in TVs, in motion pictures, and in mobile games, etc.
Computer graphics are made up of many pixels. A pixel is the smallest unit of graphics that appear on a computer screen.
The term computer graphics was first used by Verne Hudson and William Fetter in 1960.
When we draw a picture on a piece of paper, we use pencil, color, and eraser. If something goes wrong while drawing in paper, then we erase it with rubber, then it becomes stained or black and if the color is wrong, then we have to draw again in another paper, which is a difficult and laborious task.
To avoid this problem and to make a picture easily, we use computer graphics. Through which we can draw any picture. Any change in it like rotating, swapping colors, shifting the picture, etc. can do many things.
Computer graphics are used in painting, desktop publishing, building architectures in AutoCAD, making games, making movies, weather forecasting in science, etc.
Types of Computer Graphics
There are two types of computer graphics, which are the following.
- Interactive Computer Graphics
- Non-Interactive Computer Graphics
Interactive Computer Graphics
Interactive computer graphics are graphics in which the user has control over the picture, that is, the user can make any kind of change in the image.
It has two-way communication between the user and the computer. Nowadays all work stations and computer systems use interactive computer graphics.
Example:-
- Draw an image in a touch screen
- video games में graphics
- Animation in a movie
In interactive computer graphics, users make a request to the computer through the input device, and the computer changes the picture or image according to the request sent by the input device. The user can give any number of commands through the input device and the computer generates pictures according to those commands.
Non Interactive Computer Graphics
Non-interactive computer graphics are also called passive computer graphics.
Passive computer graphics are those graphics in which the user does not have any kind of control over the picture or image that appears on the computer, that is, the user cannot interact with the pictures and cannot make any changes in the pictures.
The user can only view the image on the computer and cannot make any changes to it.
There is only one-way communication between the user and the computer.
An example of this –
- Screen savers
- Static images used in a website or app
- TV shows
Interactive and Non-interactive Computer Graphics
The differences between them are as follows:
| Interactive | Non-interactive |
| It requires user interaction. | It does not require user interaction. |
| In this, the user has complete control over the image. | The user has no control over the image. |
| There is a two-way communication in this. | It has one-way communication. |
| It is programmed in such a way that the user can control the graphic. | It is completely controlled by the program. |
| Example – Graphics in Video Games, and Movies | Example – Titles shown on TV, and screen savers, etc. |
Applications of Computer Graphics in Hindi
It is used in many places which are given below:-
- In Computer Art,
we can create great art by using computer graphics. Through this, we can create cartoons, logo designs and paintings. - In education,
the use of computer-generated models in teaching is very beneficial. This makes it very easy to explain the concept of any subject. With the help of graphics, students learn easily and their interest towards the subject increases. - In video games –
Video games are electronic games in which some pictures are seen by the user on the screen with which he interacts. All these video games are made with the help of graphics. - In architecture –
It is used by architects to create pictures of buildings. - In Entertainment –
Nowadays it is used most in the field of entertainment such as – in making movies, in television shows, in motion pictures and in music videos etc. - It
is used in training so that employees can train well in a short time. For this, training modules are created with the help of computer graphics. - In machine drawing, it
is used to design many parts of the machine. - In the graphical user interface,
computer graphics are used to create the user interface. It has pictures, icons, pop-up menus, etc.
Read this in full:– Applications of computer graphics in Hindi
Advantages of Computer Graphics in Hindi
The benefits are as follows:-
- This gives us high-quality images on the computer.
- It provides tools that allow us to create real-world objects. With these tools, we can create 2D, 3D and even 4D images.
- Computer graphics have the ability to show moving pictures. Therefore, through this we can create animation.
- Through computer graphics, the user can also control the speed of animation and the view of a part of the image.
- It also has the facility of update dynamics by which the shape and color of the picture and other properties can be changed.
- It also has a low cost of designing an image.
Disadvantages of Computer Graphics in Hindi
The disadvantages are as follows:-
- Its biggest disadvantage is that computer graphics are not easy to create.
- It requires training before experimenting. It requires skills.
- Computer-based graphics software has to be constantly updated, which costs a lot of money.
- It takes a lot of time and effort to design images or pictures.
What is Display processor
Computer Graphics
display processor in computer graphics
It is an interpreter or piece of hardware that converts the display processor code into pictures.
In other words, "a display processor is used to convert digital information from the CPU to analog."
This digital-analog conversion depends on the type of display device and depends on the graphics functions.
The main function of display processors is called scan conversion. In this process, contiguous graphics objects have to be separated as a collection of ellipses, rectangles, and polygons.
The display processor is sometimes called the Display Processing Unit (DPU).
There are four main parts of the display processor, which are as follows:-
- display file memory
- display controller
- display generator
- display console
Display file memory
It is used to generate pictures. And it is also used to indentify graphic entities.
Display Controller
This display controls the operation of the device. It is also called a video controller. Its functions are as follows.
1:- It handles interrupt.
2:- It maintains timing.
3:- It is also used to interpret instruction.
Display Generator
1:- It is used to generate character.
2:- It is used to generate curves.
display console
It contains CRT, light pen, and keyboard and deflection system.
CRT
What is CRT?
- The full name of CRT is Cathode Ray Tube. It is a technology used in older computers and televisions.
- A CRT is a special type of vacuum tube that consists of a type of electronic beam that hits a phosphorescent surface, causing images to appear on the screen.
- In other words, "A CRT is a device that converts an electrical signal into a video signal." Due to which we see pictures on the screen. ”
- A CRT is a display that creates pictures in the form of a video signal. This display helps to show pictures and videos in TVs and monitors.
- This tube contains one or more electron guns and a phosphor surface that helps to show things on the screen.
- It has electron guns of three colors (red, green and blue) which we call RGB in short form.
- CRT is also known as picture tube which was the only option for display devices in the old days. However, in today's time, there are many types of display devices that help to show pictures on the screen such as LCD and LED etc.
- CRT was invented by Ferdinand Braun.
- There are two types of it, the first is Monochrome CRT and the second is Color CRT.
Types of CRT
There are two types:
1- Monochrome CRT
Monochrome CRT only displays one color. It displays graphics and pictures in one color only.
In Monochrome, mono means "one" and chrome means "color". Therefore, monochrome means a color.
It has only one electron gun that helps to show pictures. Monochrome CRTs, also known as black and white, were used in early computers to display pictures.
Aluminum is used to make Monochrome CRT. It involves many of the functions of aluminum, such as managing light, managing heat from the CRT, absorbing electrons, and preventing phosphors from burning.
2- Color CRT
It is a CRT that produces red, green, and blue. The reason why it produces three different colors is that color CRTs use different phosphors.
This CRT consists of three types of electron guns that help produce red, green, and blue.
Features of CRT in Hindi
It has the following features:-
1- Size
The size of the CRT is larger. The larger its size, the larger the diameter of the screen. The size of a CRT can be up to 1, 2, 3, 5, and 7 inches. If the CRT has a 5GP1 number, it means that it is 5 inches in size.
2- Contrast
CRT is a technology that provides more contrast. This means that it shows darker images better. CRT provides a higher amount of contrast than LCD.
3- Cost
CRT technology is not very expensive. If you go to buy it in the market, you may not get it. Because CRT is no longer produced, due to which people have to face a lot of problems in finding it.
Advantages of CRT in Hindi
1- It is a much cheaper technology than LCD and LED.
2- Its response time is very fast.
3- The CRT has a high pixel resolution, due to which it displays high-quality pictures.
4- It can produce more colours.
5- They can also be used in a dark light place.
6- Light can be increased by converting light into it.
7- It is capable of displaying high quality pictures and videos.
Disadvantages of CRT in Hindi – Disadvantages of CRT
1- The size of the CRT is large, due to which more space is required to store it.
2- They are quite heavy, which the user has to face problems in carrying somewhere.
3- It uses a very large amount of electricity.
4- It produces a large amount of heat.
5- Flat-panel displays are more expensive than displays.
Components of CRT in Hindi
1- Electron Gun − It generates electron beams.
2- Anodes − They increase the speed of electrons.
3- Fluorescent Screen − It is made of phosphor. It emits light when electrons collide on it.
4- Horizontal and Vertical Deflection Plates − These plates create magnetic fields to give the right direction to the electron beam.
5- Evacuated Glass Envelope – It holds the entire CRT together.
Components of CRT
1- Electron Gun − It generates electron beams.
2- Anodes − They increase the speed of electrons.
3- Fluorescent Screen − It is made of phosphor. It emits light when electrons collide on it.
4- Horizontal and Vertical Deflection Plates − These plates create magnetic fields to give the right direction to the electron beam.
5- Evacuated Glass Envelope – It holds the entire CRT together.
Raster scan display and random scan display
What is a Raster Scan Display?
The raster scan display is a scanning technology in which the electron beam moves along the screen. It moves from top to bottom, covering one line at a time.
When the electron beam moves in each row, the beam intensity is on, on, and off to create a pattern of illuminated spots.
The picture definition is stored in a memory area called a refresh buffer or frame buffer. This memory area holds a set of intensity values for all screen points. The intensity values are then retrieved from the refresh buffer and appear in a row (scan line) on the screen.
Each screen point is called a pixel (picture element). When one scan line is over, the electron beam moves to the left side of the screen and is ready to display the next scan line.
You can see in the picture below:
Raster scans are most commonly used to display images on a CRT screen.
advantage of raster scan display
The benefits are as follows:-
1:- It can show very realistic pictures.
2:- It can emit millions of unique colors.
3:- It can show shadow scenes.
disadvantages of raster scan
1:- Its resolution is low.
2:- It offers a zig-zag line.
What is a random (vector) scan display?
In this technique, the electron beam points only to the area of the screen in which the picture is to be drawn. It does not have left-to-right and top-to-bottom scanning like a raster scan.
इसे vector scan, stroke-writing display या calligraphic display भी कहते है.
In this, the picture definition is stored in a memory area as a group of line-drawing commands. This memory area is called the Refresh Display File.
Each component line is drawn by the commands in the display file to show a specific picture. When all the line drawing components are processed, the system cycle reverts to the first line command in the list.
advantage of random scan display
1:- Its resolution is very high.
2:- Animation is simple in it and you can draw in different positions.
3:- Memory is required very little.
disadvantage of random scan in hindi
1:- The ability of colors is very low in it.
2:- Screen density is very low so that we can draw complex images.
3:- It cannot show realistic images.
4:- It is also expensive.
difference between raster scan and random scan display
The difference between them is as follows:-
| …….. | Raster scan | Random scan |
|---|---|---|
| Resolution | Its resolution is very low because the picture definition is stored as the intensity value. | Its resolution is high because the picture definition is stored as a group of line commands. |
| cost | It is less expensive than a random scan. | It is more expensive than a raster scan. |
| refresh rate | Refresh rate- 60 to 80 frames per second. | Refresh rate is 30 to 60 times per second. |
| picture definition | It stores the picture definition in a refresh buffer. | It stores the picture definition in a refresh display file. |
| line drawing | It provides a zig-zag line because the plotted value is different. | This provides a smooth line because the line path is followed by the electron beam. |
| image drawing | It uses pixels to draw the image. | It is used to draw applications and mathematical functions. |
What is CRT? Working, Types, Features, Advantages and Disadvantages
The CRT monitor is considered to be the oldest and earliest display device in computer history. Its full name is Cathode Ray Tube Monitor. It was developed in the mid-20th century and was used in computers and television for nearly fifty years.
One of the biggest hallmarks of this monitor is its bulky and protruding back. These monitors, which looked like old-fashioned TVs, took up a lot of space on the desk. Still, the quality of their picture was extremely clean and full of colors. It was a great time option for those watching videos and playing games.
What is a CRT Monitor? (What is CRT Monitor?)
A CRT monitor is a cathode Ray tube-based display device that displays high-quality images, graphics, and color images on the screen through electron beams. It is heavy, embossed at the back, and has a strong texture.
History of CRT Monitor
The history of CRT monitors dates back to the end of the 19th century. Its development gradually took place with the contribution of many scientists and inventors.
- Early discoveries (1890 – 1920)
- CRT technology originated in 1897, when German physicist Karl Ferdinand Braun invented the first cathode ray tube.
- For this invention he received the Nobel Prize in Physics in 1909.
- This tube of Brown became famous as the "Brown Tube", which later became the basis of CRT technology.
- Television era (1920 – 1950)
- In the 1920s, scientists began using CRTs as television screens.
- In the 1930s, CRT-based TVs began to appear in the US and Europe.
- After World War II (after 1945), CRT technology developed rapidly and became commercially popular.
- Use as a computer monitor (1950 – 1980)
- In the 1950s, CRTs began to be used as displays in mainframes and minicomputers.
- Early monitors only showed text (Monochrome).
- In the 1970s, color CRT monitors were developed, using RGB technology.
- The Modern CRT Monitor Era (1980 – 2000)
- In the 1980s–90s, the CRT monitor was extremely popular due to its great picture quality and durability.
- In that era, they were experimented with VGA (Video Graphics Array), SVGA and XGA technologies.
- CRT was the dominant display technology in gaming, graphic design, and multimedia.
- Decline and End (after 2000)
- After 2000, with the advent of flat-panel technologies such as LCD, LED, and OLED, the use of CRTs gradually began to decline.
- CRT monitors almost ceased after 2010 and are now only found in older equipment or laboratories.
Working Principle of CRT Monitor
The CRT (Cathode Ray Tube) monitor is based on old technology, which generates light itself. It consists of a special tube, in which the electron beam (electron rays) collide on the screen to create images.
The process of creating a picture on the whole screen takes place in the following steps:
- Electron Gun
- The basis of the functioning of a CRT monitor is an electron gun. The cathode present in it emits rays of electrons when heated. When these rays hit the phosphor layer of the screen, it glows and we see the picture.
- The old black and white (or monochrome) monitors had only one electron gun, which produced white or green light on the screen.
- At the same time, color CRT monitors have three different electron guns: one for the red color, another for the green color, and the third for the blue color. These three guns work to shine phosphor points, giving a colorful picture.
- Control Grid
- Right in front of the electron gun is the control grid, which controls the intensity of the electron beam. This affects the brightness and colors on the screen:
- Higher Voltage: More electrons are emitted, leading to a brighter glow and brighter complexion.
- Low Voltage: Low brightness and blurry color looks due to low electrons.
- Zero Voltage: The electrons stop, causing the black color to appear on the screen.
- It is this control that makes it possible to have different brightness levels and a variety of colors on the screen.
- Focusing System
- A focusing system is used to make the electron beam a thin and focused beam. It consists of electromagnetic or electrostatic lenses, which focus the beam.
- This creates a clear and sharp picture on the screen. If the focusing is not correct, the picture appears blurry.
- Deflection Coils
- The deflection coils bend the electron beam to the correct location on the screen. These coils generate magnetic fields, which move the beam up and down and right-left. This creates a complete picture on the screen.
- Horizontal Coils - Rotate the beam from left to right
- Vertical Coils - Rotate the beam from top to bottom
- Phosphor Coated Screen
- On the inside of the screen there is a layer of a special substance called the Phosphor Coating. When high-speed electrons collide on it, the phosphor substance glows and produces light.
- This light forms the basis of the images and graphics that appear on the screen.
- How is the picture made? (Image Formation)
- Electron rays scan the entire screen very quickly (several times a second). When phosphors glow, our eyes see images constantly.
Types of CRT Monitor
There are mainly two types of CRT monitors:
1. Monochrome CRT Monitor
- The Monochrome CRT monitor displays only one color (often green, white or yellow).
- It has only one electron gun.
- The phosphor coating on the screen produces the same color light.
- It is cheaper and simpler than color CRT.
- The main use was in old computers and terminals.
2. Color CRT Monitor
- Color CRT monitors use three electron guns.
- Each gun produces a special color:
- Red Gun – for Red
- Green Gun (Green) – for Green
- Blue Gun – for Blue
- The three electron beams collide on a phosphor coated screen to create color.
- The combination of RGB (Red, Green, Blue) produces millions of colors.
- This makes clear and colorful images appear on the screen.
Features of CRT Monitor
- High Refresh Rate: CRT monitors have a higher refresh rate (the speed at which the picture is updated frequently), making moving photos appear smoother.
- Wide Viewing Angle: The CRT monitor can be viewed from any angle — color or brightness doesn't make much difference.
- Good Color Quality: This monitor is capable of showing accurate and deep colors. It was especially loved in the old times for gaming and graphics.
- Fast Response Time: CRT monitors have a very fast response time, so there is no "lag" in video and gaming.
- Low Cost: In the old days, the manufacturing cost of a CRT monitor was low, so it was a budget-friendly option.
- Strong and Durable: CRT monitors are constructed from heavy glass and strong metal, making them durable and functioning without breakdowns for years.
Limitations or Disadvantages of CRT Monitor
- Bulky and Heavy: CRT monitors are very large and heavy, making them difficult to move from one place to another.
- High Power Consumption: These monitors consume a lot more power than modern monitors, due to which they also used to heat up quickly.
- Limited Screen Resolution: Although it supports various resolutions, it has a lower resolution and limited clarity compared to modern high-definition displays.
- Radiation Emission: CRT monitors emit a small amount of radiation, which can be harmful to the eyes and skin.
- Flicker Problem: The screen in a CRT monitor is constantly refreshing, causing flickering. It can cause eye pain, fatigue, and headaches when viewed for long periods.
- Not Eco-friendly: They contain lead and other harmful elements, which are harmful to the environment.
CRT मॉनिटर बनाम आधुनिक मॉनिटर (CRT Vs Modern Monitor
speciality CRT Monitor Modern Monitor (LCD/LCD) LED / OLED) Size and weight Heavy and large, protruding from the back Slim, lightweight and stylish Power consumption Consumes more electricity Consumes less power, energy-efficient Screen Quality Colors are good, but high resolution is limited. High resolution (Full HD, 4K), color very accurate Refresh Rate and Response Time Fast response time, good in gaming LED and OLED monitors also have faster refresh rates, HDR and better graphics support Viewing Angle Can be seen from any direction The viewing angle may be limited in LCD, wider in OLED. Contrast & Black Levels Colors nice, but blacks not too deep Deep black and high contrast in OLED Durability and Construction Strong, heavy glass and metal Lightweight, thin, emphasis on design Radiation Light radiation, effect on the eyes when seen for a long time Very little or negligible radiation, safe utility For older computers, gaming, and graphics Modern computers, laptops, TVs, professional graphics and gaming
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