Graphic definitions

Summary of Chapter 10 of the Non-designer’s web book by Robin Williams and John Tollet.

Pages (172-179)

Miss Mary Victor

File FormatsFile format is the type of file.

You can find out the type by the extension.For example .gif, jpg and png are extensions for image

type files, .mov is for movie and .html is a website. We shall focus on different image formats.

but before that you need to know..

Native file formatis the format native to or natural to the program, for instance when you save in

Microsoft word the program automatically saves the file as a word document (.doc,

docx) that is the native file to the program. Sometimes you have the option

of saving the file in more than one format.

Graphic File Formats

Vector images

Based on mathematical formulas.

The application has the word “draw” or “illustrate” in the name. ex. Illustrator.

Pixels images

Based on pixels (dots on a screen)

The application usually has the word “paint” or “photo” in the nameex. paint brush& photoshop

There are two kinds of graphic files

Graphics on the web are pixel

based.

GIF Images

pronounced “gif” not “jif”.

Developed by CompuServe.

Stands for Graphic Interchange Format.

Gifs Properties 1

They are cross platform :work on any computer.

They are compressed (Small in size)for ex. Tiff image 2*2 could be 900Kwhile Gif of same dimension is 5K.

The small in size helps in fast file transfer on the internet.

Gif properties 2

Animation. The only format with which you can create moving pictures is GIF.

Transparency : images shows through the background.

interlacing: allows for layers.

GIF Color

Lossless compression

uses index color : a maximum of 256 colors

GiF is Best for

logos, simple images or cartoons

JPEGs

pronounced “jay peg”.

Stands for Joint Photographic Experts Group.

JPEG PropertiesCross platform: work on many computers.

Does not allow for Transparency thus all files are rectangular in shape.

Not interlaced. No layers. Thus you have to wait for image to work its way down slowly.

JPEG Color

up to 16.7 Million color!

Hence they are better in photographs, watercolor images, pencil or charcoal drawings.

JPEG is Best for?

photographs & images with Details: depth, lightening effect and graduations of colors and tones.

PNGs

pronounced “Ping”

stands for Portable Network Graphics

PNG Properties

Alpha level:It has 256 LEVELS of transparency.

Interlaced: So you see an image immediately that gradually loads in detail

Gamma level: PNG is smart enough to have a property (the gamma) that can detect screen type and adjust brightness accordingly!

PNG Colors

Can have 256 colors or 16.7 Million or greyscale !!

Pointof

ComparisonGIF JPEG PNG

Stands forGraphical

Interchange Format

JointPhotographic Expert Group

PortableNetworkGraphics

Animation ✔ ✖ ✖

Interlacing ✔ ✖ ✔

Transparency

✔ ✖ ✔ 256 levels

Gamma ✖ ✖ ✔

Color 256 Colors16.7 Million

colors

256, or 16.7 Million or greyscale

Best for?Logos, text,

simple images, cartoons

Digital photographs with details

(rectangular)

Summary of Main points