Introduction toIntroduction to

Computer GraphicsComputer Graphics

Raster Vs. VectorRaster Vs. Vector

COMMUNICATION TECHNOLOGY

Intro to Computer Intro to Computer GraphicsGraphics

Computers have radically changed how graphics, photos and printed materials are produced.

What once took a highly trained artist many hours to produce with specialized equipment can now be done much easier using computer software.

Raster GraphicsRaster Graphics (write blue text)(write blue text)

Graphics are produced using a grid of small squares known as pixels. Each pixel is assigned a specific colour value and location.

When editing a raster graphics (ex. Digital photo), you are actually editing pixels rather than objects or shapes (Photoshop)

Pixels can be seen by zooming in on a digital image (tiny squares).

Raster GraphicsRaster Graphics (write blue text)(write blue text)

Raster graphics are generally larger files than vector images.

Images lose quality (become “pixelated”) if enlarged more than 20% of the original size.

Vector GraphicsVector Graphics (write blue text)(write blue text)

Drawing programs such as CorelDraw and Adobe Illustrator produce vector graphics.

These types of graphics are made of lines and curves defined by mathematical objects called vectors

(geometric characteristics).

Vector GraphicsVector Graphics (write blue text)(write blue text)

A vector graphic can be moved or resized without losing quality and file sizes are generally smaller than raster graphics.

Best choice for creating type or logos where crisp outlines are needed since clarity is not lost when scaled/resized.

Common Image Files Common Image Files (write (write blue text)blue text)

BMP: Bitmap is the standard Windows image format

GIF: Graphics Interchange Format; designed to minimize file size and download (electronic transfer) time

Common Image Files Common Image Files (write (write blue text)blue text)

JPEG: Joint Photographic Experts Group; compresses file size by selectively discarding data, unlike GIF format, JPEG retains colour information.

TIFF: Tagged-Image File Format; used to exchange files between applications and computer platforms; “flexible” bitmap image supported by virtually all paint , image editing, and page-layout applications.

Resolution Resolution (write blue text)(write blue text)

Resolution is how many pixels or dots make up the image you see.

On a monitor, resolution is measured

in pixels per inch.

Screen resolution is 72 ppi.

Resolution Resolution (write blue text)(write blue text)

Print resolution is measured in

dots per inch.

Print resolution should be at least 150 dpi.

For high quality printing, images should be

300 dpi or greater.

Print resolution depends on the printing press being used (Offset, Web etc.).