COMPUTER GRAPHICSGIMP

COMPUTER GRAPHICS

Computer Graphics are graphics created using a computer and more generally, the representation and manipulation of image data by a computer.

Developments in computer graphics have had a profound impact on many types of media and have revolutionized the animation and video game industry.

THE COURSE This is an introductory course in Computer Graphics

using the open source package GIMP. Participants should have successfully completed the Computer Literacy course of be fairly comfortable with the basics of file manipulation, input and output and the use of applications.

In this course, you will learn the basics of color composition in different color models, compression techniques and their uses. As with any computer course some tips in file manipulation would do well especially in GIMP in which at times there are so many save options.

You will master the techniques of working with canvases, image modes and colour selection, selections and masks, layers and blend modes, as well as adding and working with text, painting tools and retouching tools.

GIMP

GIMP is an image editing software. It allows you to transform scanned photographs,

slides and original artwork in many ways, for example by cropping, rotation, resizing and by creating special effects using filters ranging in effect from blurring to mosaics.

GIMP combines a full range of painting, editing and image composition tools, sophisticated selection tools, and methods for adjusting levels of grey and colour in continuous-tone images.

COMPUTER AND PERIPHERALS Computer: GX 280 Dell computers

Pentium IV 504 MB RAM 2.80 GHz Hard disk Capacity: 40GB

Operating System: Windows XP Service Pack 3

Printers: Brother MFC 9600 – B/W w scanner Lexmark X1270 – Colour printer w scanner

Cameras Eye Logitech Quick Cam

MOUSE

The Mouse is an integral part of GIMP and to make the most of the package, users must be confident in their mouse use.

Mouse operations include: Pointing – the mouse is placed over a part of an image.

This is normally a prerequisite for dragging or selecting Selecting – after pointing, the mouse is clicked or

double-clicked to select a particular menu instruction, toolbar, or part of an image.

Dragging – after pointing, the mouse button is held down while the mouse is dragged across part of the image.

LAUNCH GIMP

Start All Programs

GIMP

Follow along as we explore the interface…

Toolbox

Layers, channels and paths

Menu bar

Canvas

MENU BAR OPTIONS

File, Edit, Image, Layer, Select, Filter, View, Window Help.

Explore the menus below each to familiarize yourself!!

MENU BAR You may notice that some menu commands are

followed by ellipses (...). This indicates a command that is followed by a dialog box where you can enter additional settings.

Some menu commands are followed by a right pointing arrow. This indicates a submenu of related commands. As you explore each menu, be sure to take a look at the submenus as well.

You'll also notice that many commands are followed by keyboard shortcuts. Gradually, you'll want to get to know these keyboard shortcuts as they can be incredible time savers.

OPEN THE FILE “BLOWHOLE.JPG”

IMAGE > IMAGE PROPERTIES…

Use the menus as shown above to examine the image properties

You will notice that this image is 640 x 480 pixels

Its file size is 81.4 KB It is a JPEG image Google JPEG and learn about this

compression technique

IMAGE PROPERTIES

SOME QUESTIONS

How much compression does JPEG allow before perceptible loss in image quality?

What is JPEG an acronym for? What other compression techniques

are there? What is the more commonly used

technique these days?

DOCKABLE DIALOGS

TOOLBOX

The toolbox is located in the left hand side of the GIMP interface

Hover over each tool in turn to get to know its name and have an idea of what it does…

There are SELECTION TOOLS, PAINT TOOLS, TRANSFORM TOOLS and COLOR tools.

The Tools menu option has these categorised for your convenience

FILE STORAGE

File > Open In My Pictures, create a new folder

called “GIMP” You will store all your photos in this

folder. You should walk with a small flash drive

so that you can back up all your work from week to week.

FILE FORMATS

Type Extension

Description

GIMP .xcf For “working” images in GIMP

TIFF .tiff For exporting to other printing applications. (24-bit colour, loss-less compression possible, channel masks saved

JPEG .jpg For exporting tone-based web images. Note JPEG compresses the file by losing file information so file cannot be reworked.

GIF .gif For exporting line-based web-images.

PNG .png Emerging web standard to replace JPEG and GIF but not widely used yet.

RAW The RAW file format is digital photography's

equivalent of a negative in film photography: it contains untouched, "raw" pixel information straight from the digital camera's sensor. 

The RAW file format has yet to undergo demosaicing, and so it contains just one red, green, or blue value at each pixel location. 

Digital cameras normally "develop" this RAW file by converting it into a full color JPEG or TIFF image file, and then store the converted file in your memory card. 

Digital cameras have to make several interpretive decisions when they develop a RAW file, and so the RAW file format offers you more control over how the final JPEG or TIFF image is generated. 

COLOUR MODELS

Model Description

CYMK The CMYK color model, referred to as process color or four color, is a subtractive color model, used in color printing, also used to describe the printing process itself. CMYK refers to the four inks used in most color printing: cyan, magenta, yellow, and key black. Though it varies by print house, press operator, press manufacturer and press run, ink is typically applied in the order of the abbreviation. The “K” in CMYK stands for key since in four-color printing cyan, magenta, and yellow printing plates are carefully keyed or aligned with the key of the black key plate. The CMYK model works by partially or entirely masking certain colors on the typically white background

RGB The RGB color model is an additive color model in which red, green, and blue light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three additive primary colors, red, green, and blue.The main purpose of the RGB color model is for the sensing, representation, and display of images in electronic systems, such as televisions and computers, though it has also been used in conventional photography. Before the electronic age, the RGB color model already had a solid theory behind it, based in human perception of colors.

CMYK COLOUR MODEL

RGB COLOUR MODEL

QUESTIONS

http://www.cambridgeincolour.com/tutorials/camera-sensors.htm

http://www.digicamhelp.com/camera-features/advanced-settings/raw/