Vector GraphicsVector GraphicsAllen Academy of e-Learning

Vector and BitmapVector and Bitmap

• The two main categories of graphics

• Each has strengths and weaknesses

• They are developed very differently

• Choosing the correct format for the right project can save you time and give you added design options

Graphics on the WebGraphics on the Web

Until recently, the way to add drawings to a web page was to define the drawing as an image (in GIF, PNG, JPEG or some other format) and insert the image into the web page using the <IMG> element. This works well for many graphics. However, the following slides compare the differences and benefits of vector images.

RasterRaster = PixelsPixels

Pixel

Pixel Info:• RGB Value

1. Red (233)2. Green (56)3. Blue (156)

• Position4. X coordinate (259)5. Y coordinate (848)

File SizeFile SizeBitmap (Raster):• The file size of an

image is defined by the width and height of the image (in pixels) and the number of bits allocated to each pixel in the image.

Vector:

• File size defined by mathematical equations telling how to “draw” the image. Vectors can often be much smaller files that download faster.

Screen size = 2089 x 1094 pixels

Bitmap = 6.5 MB vs. Vector = 26 KB

ResolutionResolution

Bitmap:• Once the image has

been defined at a specific resolution (ex. 800 x 600) the graphic will not look as good at another resolution (ex. 1028 x 764).

Vector:• Vector images are

scalable to dynamically fit whatever resolution the viewer’s monitor may be. You can even zoom in on a vector without losing clarity.

HyperlinkingHyperlinking

Bitmap:• The Web depends on

hyperlinking. To have more than one link per image requires the use of image maps embedded in the HTML code.

Vector:• Various parts of a

vector image may have different links, built inherently into the image.

AnimationAnimation

Bitmap:• Minimal animation:

The GIF format allows several images to be defined in one image file ("animated gifs"), but each image is essentially static.

Vector• Flash and shockwave

files are examples of fully-animated vector drawings with many animation options.

Application of Vector GraphicsApplication of Vector Graphics

Vectors can be used to create:

• Graphics for the Web, t-shirts, bumper stickers, signs, etc.

• Architectural drawings• Animations

Digital ImagesDigital Images

““artwork” artwork” of the of the

new millenniumnew millennium

UVSC--MCT 1110UVSC--MCT 1110

The Last Supper (after cleaning)Leonardo da Vinci, 1498

Tempera on plaster 460 x 880 cm (15 x 29 ft.)

Convent of Santa Maria delle Grazie (Refectory), Milan, Italy

• Image ColorImage Color ~ Mechanics

• Image DisplayImage Display ~ Digital Artistry

• Image AdjustmentsImage Adjustments ~ Digital Environment

More than anything else, the user’s judgment of your work

will be most heavily influenced by the work’s visual impact.

--Tay Vaughn, President, Timestream

DigitalDigital ImagesImages

Image ColorImage Color :Digital MechanicsDigital Mechanics

ImageImage ColorColor: How We See ItHow We See It

• Light spectrum – colors we can see(VIBGYOR)

• Printers recreate the color spectrum with a 4 color process (cyan, yellow, magenta and black)

• Digitally we recreate with red, green and blue

ImageImage ColorColor: How We Create It ~ RGBHow We Create It ~ RGB

• Rasters ~ monitor light

• Pixels ~ picture elements

• Palettes ~ color tables

ImageImage ColorColor: How We Create itHow We Create it

• Red, Green, Blue (RGB)

- System for representing the colors on a computer display

256 x 256 x 256 = 16,777,216 16 million possible colors

– Combine to obtain any color in the visible spectrum

– 3 channels (8 bit each); 0 to 255 gives intensity range of 0-100%

ImageImage ColorColor: How Many Colors ~ DepthHow Many Colors ~ Depth

Number of Colors

Bits Required (per pixel)

Common Jargon

2 1

4 2 2 bit

16 4 4 bit; 16 colors

256 8 8 bit; 256 colors

65,536 16 (2 bytes) 16 bit; high color

16,777,216 24 (3 bytes) 24 bit; true color

• Color Depth ~ total number of colors possible per pixel

16 million(24 bit)

256Colors(8 bit)

16 colors

ImageImage ColorColor: How We Display It ~ ResolutionHow We Display It ~ Resolution

How many colors?Depth

How many pixels (per inch) ?Resolution

high medium low

Image ColorImage Color: How it Affects File SizeHow it Affects File Size

• Color Depth x Image Resolution = Image File Size

• Color Depth x (Length x Width) = Image File Size

• 16bit x (100 x 500) = Image File Size

• 2 bit x (50,000) = 100,000

Image DisplaysImage Displays:Digital Artistry

ImageImage DisplayDisplay: Digital ArtistryDigital Artistry

What is a Bitmap? …a Vector?

How are these images generated?

What are their… -- advantages?

-- disadvantages?

ImageImage DisplayDisplay: : What is a Bitmap?What is a Bitmap?

An“information matrix”

Matrix describes individual picture elements (pixel ~ “dot”) of resolution on a display screen.

Artist captures (e.g., via camera/scanner) or creates (e.g., via Photoshop) a bitmap image

Computer “reads” the bitmap’s matrix of informationComputer processes the information

Computer displays the processed information… in milliseconds

Image DisplayImage Display: How to Generate a BitmapHow to Generate a Bitmap

Photo-realistic quality

Easily handles complex subjects

Easily edited or altered

File retains all data required for re-use, etc.

Image Display:Image Display: Bitmap AdvantagesBitmap Advantages

Image Display:Image Display: Bitmap DisadvantagesBitmap Disadvantages

Not easily scale-able Huge file sizes

•Often require compression

•Most common compressionsresult in loss of image data

Reductions ~ may blur Enlargements ~ will

pixelate

Take a BREAKTake a BREAK

Stand and StretchStand and Stretch

Feel free to get a drinkFeel free to get a drink

A mathematical recipe used to “draw” an image

Series of instructionsusing lines, polygons and other geometricshapes

Image Display:Image Display: What is a Vector?What is a Vector?

Artist creates an image using drawing softwaresuch as Adobe Illustrator

Software describes the drawing tothe computer as a series of lines, curves, polygons etc.

Computer processes the information

Computer displays the processedinformation… in milliseconds

Image Display:Image Display: How to Generate a VectorHow to Generate a Vector

Easily edited or altered

Easily scalable

Very small file size

Image Display:Image Display: VectorVector AdvantagesAdvantages

Not photo-realistic

Not widely used outside of tech fields

Image Display:Image Display: VectorVector DisadvantagesDisadvantages

Image AdjustmentsImage Adjustments:Digital Environment

Image Adjustments:Image Adjustments: ComputerComputer PalettePalette

• Sets of colors – mathematical tables that define the color of a pixel displayed on the screen Normal Palette clash

• 8 bit Palette Clash/Flash only one set of 256 colors can be displayed at once

Image Adjustments:Image Adjustments: IllusionsIllusions ~ AntialiasingAntialiasing

• Smoothing of an imagecaused by aliasing(see notes)

• Adjust pixel positionsor intensities

Image Adjustments:Image Adjustments: IllusionsIllusions ~ DitheringDithering

• Large palette (16M colors) down to small palette (256 colors)

• Color value of each pixel is changed to the closest matching color in the target palette

• Uses math algorithms

16M16M 256 colors 256 colors

nonenone OO RR

LosslessLossless--retains all the original data as part of the compressed file

• .png .png (Portable Network Graphics)

• .tif.tif (Tagged Interchange Format)

• .gif.gif (Graphics Interchange Format)

Image Adjustments:Image Adjustments: CompressionCompression

• .jpg.jpg

(Joint Photographic experts Group)• .gif.gif

(Graphics Interchange Format); limited to 256 colors

Lossy--Lossy--compromises the original data and it cannot go back to the original image.

Image Adjustments:Image Adjustments: CompressionCompression FormatsFormats

Image Adjustments:Image Adjustments: Compression FormatsCompression Formats

• BMP – bitmap (Windows bitmap format)

• PICT – bitmap/vector (Apple/MAC bitmap format)--------------------------------------------------------------

• GIF – Graphics Interchange Format (256 colors; allows for transparency)

• JPEG/JPEG 2000 – Joint Photographic Experts Group (16M colors; lossy compression)

• TIFF – Tagged Interchange File Format (universal bitmap format)

• PNG – Portable Network Graphics Specification (open/universal format)

Illustrator’s Interface

• Worksheet B– Open Illustrator and name the parts of the

window.– Use the Tooltip to identify each tool and its

shortcut keystroke.