• UNIT 3: COMPUTER GRAPHICS TOOLS

    3.0 Introductory Activity


    3.1. Introduction to Computer Graphics


    Modifying a hard drawing can be hard, swapping colors or resizing a picture on such
    a drawing is more complicated. That’s why it is more efficient to draw a picture on a
    computer screen and the drawing is now a piece of digital information which is easy

    to modify. 

    Computer Graphics involves the ways in which images can be displayed, manipulated

    and stored using a computer.

    Computer graphics provides the software and hardware techniques or methods for

    generating images. 

    3.1.1. Definitions of Different Terms
    Computer graphic: This is the use of a computer and specialized programs to produce
    and manipulate pictorial images.
    Pixel: is the smallest unit of a digital image or graphic that can be displayed and
    represented on a digital displayed device. Is also known as a picture element. A pixel
    can have different colors produced by mixing the three colors RGB (Red, Green and
    Blue) and each of the three colors can take values ranging from 0 to 256.
    2D (2Dimensional) images are objects that are rendered visually on paper, film or on
    screen in two planes representing width and height (X and Y). Two-dimensional

    structures are also used in the construction of 3D objects. 

    3D computer graphics or three-dimensional computer graphics, (in contrast to 2D
    computer graphics) are graphics that use a three-dimensional representation of
    geometric data (often Cartesian) that is stored in the computer for the purposes of

    performing calculations and rendering 2D image.

    Morphing: is a technique which involves using a computer to make an image on film
    or television appear to change shape or change into something else. For example a
    human face may be transformed into a lion one and the human eye will find it
    unbelievable how the human has changed him/herself.
    Random scan:
    Random Scan System uses an electron beam which operates like a pencil to create a
    line image on the CRT (Cathode Ray Tube) screen. The picture is constructed out of a
    sequence of straight-line segments. Each line segment is drawn on the screen by
    directing the beam to move from one point on the screen to the next, where its x & y
    coordinates define each point. After drawing the picture. The system cycles back to
    the first line and design all the lines of the image 30 to 60 time each second.
    The process is shown in figure:

    Source: : https://www.javatpoint.com/

    Raster scan
    A raster scan display is based on intensity control of pixels in the form of a rectangular
    box called Raster on the screen. Information about On and Off pixels is stored in a
    refresh buffer or Frame buffer. Televisions in homes are based on Raster Scan
    Method. The raster scan system can store information of each pixel position, so it is
    suitable for realistic display of objects. Raster Scan provides a refresh rate of 60 to 80
    frames per second.

    Frame Buffer is also known as Raster or bit map. In Frame Buffer the positions are
    called picture elements or pixels. Beam refreshing is of two types. First is horizontal
    retracing and second is vertical retracing. When the beam starts from the top left
    corner and reaches the bottom right scale, it will again return to the top left side called
    at vertical retrace. Then it will again more horizontally from top to bottom. The figure
    below illustrates the process



    3.2.1. DEFINITION
    Image file formats are standardized means of organizing and storing digital images.
    Image files are composed of digital data in one of the formats that can be rasterized
    for use on a computer display or printer.
    There are 4 main formats in which to store images including TIFF, JPEG, GIF and PNG.

    Their differences are given in the table below:

    3.2.2 Image compression
    Image compression is minimizing the size in bytes of a graphic file without degrading
    the quality of the image to an unacceptable level. The reduction in file size allows
    more images to be stored in a given amount of disk or memory space. It also reduces
    the time required for images to be sent over the Internet or downloaded from web
    pages. Know an image’s file size and dimensions before or after uploading it into the

    Library

    Image compression techniques Lossy and Lossless
    Lossless: The compression technique where compressed data (byte) will be the same
    replica of actual data. In this case, compressed file is required to be reproduced
    exactly when get decompressed again.
    Lossy: File compression results in lost data and quality from the original version. Lossy

    compression is typically associated with image files.

    3.2.3 Viewing an image’s file size and dimensions
    The determination of an image’s file size and dimensions depends on an Operating
    System being used.
    Open the image in Windows Explorer to check dimensions and file size by clicking the
    Windows Start button on the taskbar.
    Right clicking the icon of the image file,
    In the pop up menu, click on property and details.
    The result will look like below. The wanted information are circled with red line. 

    3.2.4 Calculating size of an uncompressed image file
    Computer storage and memory is measured in Megabytes (MB) and Gigabytes (GB).
    A bit is the smallest unit of measurement used to quantify computer data and byte is
    a group of 8 binary digits.
    Unit of memory size.
    1Byte= 8bits
    1KB= 1024Bytes
    1MB = 1024 KB
    1GB=1024 MB
    1TB=1024 GB

    It takes 2 to 3 bytes to store one pixel of a color image. The pixels in an image store a
    color at a given point in the image, but it takes 2 to 3 bytes of storage to record this
    value. If we consider 3 bytes of storage, the file size of a color image is equivalent to:
    width * height * 3
    Example: Let‘s consider an image whose Width is 1152 and height is 648.
    If we consider 3 bytes of storage, the file size of a color image is equivalent to: width
    * height *
    3 which is =1152*648*3 = 2,239,458 which gives the file size in bytes. This
    file size number is so big, it needs to be converted in Kilobytes or even megabytes.
    There are 1,024 bytes in a kilobyte and 1,024 kilobytes in a megabyte which makes
    this file have the size of 2.187 Kilobytes.


    3.3 Image Capturing Tools 


    The process of obtaining a digital Image from a vision sensor, such as camera usually
    entails a hardware interface known as a frame grabber, which captures single frames
    of video, converts the analogue values to digital, and feeds the results into the

    computer memory.

    3.3.1. Digital Camera
    The first digital camera was invented by STEVEN SASSON in 1975. Digital cameras are
    normally used to capture pictures or video through the use of an electronic image
    sensor.
    There are two types: 
    3.3.1. Digital Camera
    The first digital camera was invented by STEVEN SASSON in 1975. Digital cameras are
    normally used to capture pictures or video through the use of an electronic image
    sensor.

    There are two types: 


    a. Definition
    A digital camera is a camera which produces digital images that can be stored in a
    computer and displayed on screen. It records and stores photographic images in
    digital format.
    These stored images can be uploaded to a computer immediately or stored in the
    camera to be uploaded into a computer or printed later.

    Digital cameras use an image sensor instead of photographic film. 


    Digital camera parts
    There are 10 basic camera parts to identify in today’s digital world. These parts will
    inevitably be found on most cameras being digital compact or single-lens reflex
    camera (SLR)
    Lens
    The lens is one of the most vital parts of a camera. The light enters through the lens,
    and this is where the photo process begins. Lenses can be either fixed permanently to
    the body or interchangeable. They can also vary in focal length, aperture, and other
    details.
    Viewfinder
    The viewfinder can be found on all digital single-lens reflex cameras (DSLR) and some
    models of digital compacts. On DSLRs, it will be the main visual source for image taking,
     but many of today’s digital compacts have replaced the typical viewfinder with

    Liquid Crystal Display (LCD) screen.
    Body
    The body is the main portion of the camera, and bodies can be in different shapes and
    sizes. DSLRs tend to be larger bodied and a bit heavier, while there are other consumer

    cameras that are a conveniently smaller size and even able to fit into a pocket.

    Shutter Release
    The shutter release button is the mechanism that “releases” the shutter and therefore
    enables the ability to capture the image. The length of time the shutter is left open
    Aperture
    The aperture affects the image’s exposure by changing the diameter of the lens
    opening, which controls the amount of light reaching the image sensor. Some digital
    compacts will have a fixed aperture lens, but most of today’s compact cameras have
    at least a small aperture range.
    Image Sensor
    The image sensor converts the optical image to an electronic signal, which is then sent
    to the memory card. There are two main types of image sensors that are used in most
    digital cameras: Complementary Metal-Oxide-Semiconductor (CMOS) and Charge
    Coupled Device (CCD) Both forms of the sensor accomplish the same task, but each

    has a different method of performance.
    Memory Card
    The memory card stores all of the image information, and they range in different size
    and speed capacity. Memory cards can be taken out of the camera and inserted in a
    computer memory card bay for reading.

    LCD Screen

    The LCD screen is found on the back of the body and can vary in size. On digital
    compact cameras, the LCD has typically begun to replace the viewfinder completely.
    On DSLRs, the LCD is mainly for viewing photos after shooting, but some cameras do

    have a “live mode” as well. 

    Flash
    The on-board flash will be available on all cameras except some professional grade
    DSLRs. It can sometimes be useful to provide a bit of extra light during dim, low light
    situations.
    User Controls
    The controls on each camera will vary depending on the model and type. The basic
    digital compacts may only have auto settings that can be used for different
    environments, while a DSLR will have numerous controls for auto and manual

    shooting along with custom settings. 

    c. Importing pictures using USB cable
    The images taken by using a camera are stored automatically in its memory. However,
    for different purposes, the images can be printed or inserted in documents for 
    illustrations. The camera is then connected to the printer or the computer by using a
    USB cable appropriately designed for such action. The fact of taking pictures from the

    camera to the computer is called importing pictures. 

    The following steps are followed to successfully import a picture from camera to
    computer by using a USB cable.
    Step 1: Connect one end of the USB cable to the port in your camera.
    Step 2: Connect the other end of the USB cable to the USB port in the computer. This
    may be in the front or back of the computer.
    Step 3: Turn on the camera
    Step 4: A dialog box may appear on the screen. If it does, select “View Files” or “Open
    Folder.” If the dialog does not appear, click the Windows “Start” menu, select

    “Computer” and then choose the drive labeled for the connected camera.

    The pictures are probably located in a particular photo folder on the camera. Open
    that folder. Drag individual photos from the folder to the desktop or some other folder
    on the computer. All the photos can be selected by pressing “Ctrl-A” and then pasted

    into a folder on the computer by pressing “Ctrl-V

    3.3.2 Scanner

    A scanner is an electronic device which can capture images from physical items
    (printed text, handwriting, photographic prints, posters, magazine pages, and similar
    sources) and convert them into digital formats, which in turn can be stored in a
    computer and viewed or modified using software applications.

    Very high resolution scanners are used for scanning for high-resolution printing, but

    lower resolution scanners are adequate for capturing images for computer display. 

    b. The different parts of scanner
    A scanner has the following five parts visible externally:
    (1)Start button, (2) Copy button, (3) Scan to E-mail button, (4) Scan to Web button, (5)

    Scanner cover

    Note:
    Parts, size and looks of scanners vary depending on the type of scanner and some scanning
    and photocopying functionalities are combined in one physical device therefore some of the
    parts mat not be visible
    Some scanners have touch screen capabilities therefore they may not have some of the

    buttons

    3.4 Screenshots Capturing



    A screenshot is an image of a computer desktop that can be saved as a graphic file. (The mouse
    cursor is not included in the image). The main ways used to get the screen of computer is to
    use the Print Screen key (PrtSc) or the Snipping Tool

    3.4.1. Use of Print Screen Key

    A print screen is a computer key which is used to copy to the clipboard an image of the screen
    and paste it in any other application for saving or manipulation
    Steps to follow in screen shot capturing using Print screen key:
    Open the screen that is going to be copied.
    Press the Print Screen key

    Paste (CTRL+V) the image into an Office program or any other application.

    The taken image can be edited depending on the options provided by the program in which

    it is pasted. 

    3.4.2 Use of Snipping tool
    Snipping Tool is a Microsoft Windows screenshot utility included in Windows Vista and in
    later versions. It can take still screenshots of an open window, rectangular areas, a free-form

    area, or the entire screen.

    To open the Sniping tool:
    Click on Start
    Write Snipping Tool in the search box and once found click on it to launch or click on All
    Programs then click on Accessories and click on the snipping tool 
    An opened Sniping tool will look like in the image below:

    To take a screenshot using Snipping tool

    To take a screenshot in the opened Snipping tool

    3.5. Graphic Software-Paint


    In computer graphics, graphics software refers to a program or a collection of
    programs that enable a person to manipulate images on a computer.

    Examples of such programs include Adobe Photoshop, Microsoft Publisher, Paint, Etc.

    3.5.1. Starting and saving a Paint file
    A paint program is a software graphics program that allows the user to draw or paint
    bitmapped images on a computer.

    To start Paint go through the following steps:

    Understand the canvas
    When Paint launches, the white “canvas” will appear on the screen. Imagine this
    canvas as a piece of paper to draw or write on. The size of the canvas can be adjusted

    before starting to create images.

    The flower above has been drawn using the Pencil tool which was used to draw lines

    and the Fill with color tools was used to fill the red color on the leafy part of the flower. 

    Saving a paint file

    From File menu, choose Save as.

    From a dialog box, choose PNG picture or any other image file format


    In the next window type the file name, choose file format then click on save button.
    3.5.2. Paint tools
    The paint program has got many tools which help its user manipulate images and do
    any activity Paint is supposed to do. Some of the Paint tools are shown in the image

    below:


    Text tool: The tool allows text to be typed onto the current layer using the primary
    color. The text controls in the Toll Bar can be used to change the font, the size of the

    font, formatting.

    The pencil tool: is a freehand drawing tool, much like an actual pencil. The width of
    the line can be adjusted by clicking the Size menu and selecting a different line width.

    To draw, simply press the mouse button as you move the mouse on the canvas.


    Eraser tool: This tool is used to remove parts of the active layer or selection like in

    the image below

    Color picker tool: is used to select a color on the active layer. By clicking a point on a
    layer,
    You can change the active color to that which is located under the pointer.


    Magnifier: next to the “Pick color” button is the “Magnifier” button, which looks like
    a magnifying glass. Selecting this tool will allow the user to zoom in and out of an

    image.

    3.5.3. Insertion of Shapes

    A shape is a geometric figure such as square, triangle or rectangle. Using illustrator’s
    shape to draw can be an effective way to create smooth paths and predictable results.

    Below are different shapes in Paint:

    Select any shape from the toolbar to draw that shape. Once you’ve chosen a shape,
    you’ll notice some options for the shape’s appearance.
    Click the “Outline” and “Fill” menus to view your options.
    Select your preferred outline and fill options,
    Then, click the canvas where you’d like to place your shape.
    Hold down the mouse button as you drag the cursor to enlarge the shape.
    Let go of the mouse button when reach the desired shape size.
    After choosing a shape with an outline, the color of the outline will be the current
    foreground color. If the shape has a solid filling, the fill color will be the background
    color.
    3.5.4. Select, Cut, Copy, Paste and Crop
    a. Copy and Paste
    Press and hold down the left mouse button inside the selection box and move the
    picture to relocate the image. 

    If you wish to copy the image:

    Right-click inside the selection box

    And click "Copy."

    An image can be pasted to another paint document or in another program

    b. Cut and Paste

    Click on the area of an image you want removed, click and hold the mouse to drag

    the box as far down and over as needed

    Press and hold "Ctrl" and "X" to cut the selection.

       Press and hold "Ctrl and "V" to paste the selection, either elsewhere in the
    same document or in a separate document.


    Paste in Ms Office word


    After cutting in Paint

    c. Crop

    Select the portion of the image you want to crop using the Select tool.
    Once selected right-click with the mouse anywhere in the image selection and

    select Crop or go to Crop in tools bar.






UNIT2: ADVANCED POWER POINTUNIT 4: E COMMERCE, SOCIAL MEDIA AND ONLINE SERVICES