graphic file formats

Graphic File Graphic File FormatsFormats

ObjectivesObjectives• Understand the difference between two

major categories of computer graphic images

• Investigate the differences between various file formats

• Generalize formats to the type of software that creates them

• Establish a philosophy of use for various graphic file formats

A usable description of any software's proprietary file format.

Native File FormatNative File Format

Two Categories of Two Categories of FormatsFormats

Bitmapped Vector

Bitmapped FormatsBitmapped Formats• Images are

created by individual pixels displayed in various colors.

Bitmapped FormatsBitmapped Formats• Remember,

each pixel can hold up to 24 bits (3 bytes) of color information

Bitmapped FormatsBitmapped Formats• Bitmapped

formats have a fixed resolution

• Can NOT be resized without some effects on the clarity of the image

Bitmapped FormatsBitmapped Formats

• Bitmapped formats are best suited for “photographic” quality images

Bitmapped FormatsBitmapped Formats• Scanners and

digital cameras acquire images in bitmapped formats

Common Bitmapped Common Bitmapped File FormatsFile Formats

• TIF

• JPG

• BMP

• PIC

• GIF

• PNG

• PSD

• PCX

TIF FormatTIF Format• Tagged Image File

format.• Standard between

MAC and PC bitmap graphics.

• Handles multiple channel files.

• i.e. RGB• i.e. Alpha Channels

TIF FormatTIF Format• Writes a "header"

that tells software what information is contained.

• Header may increase file size.– Not really a

problem with modern hardware

TIF FormatTIF Format• Uses a LZW

compression scheme.

• No data lost, just compressed.

JPG (Jpeg) FormatJPG (Jpeg) Format• Joint Photographic

Experts Group• A file format and

compression scheme.

• Emerging as a standard format for photos.

• Internet use.

JPG (Jpeg) FormatJPG (Jpeg) Format• “Lossy”

compression-• Reduces data

during save.• Data loss can be

controlled.• Can reduce file size

in a ratio between 10:1 and 20:1.

BMP FormatBMP Format• Microsoft native file

format

• PC system compatible– DOS– Windows– OS/2

• No MAC compatibility.

BMP FormatBMP Format• Photoshop encodes to

1, 4, 8, 24 bit color but .bmp can not support channels.

• No file space savings for photos with .bmp.

• - Try a JPG!

PIC (Pict) FormatPIC (Pict) Format• A MAC native file

format.• Not PC operating

system compatible.• Can do 24 bit color plus

an extra 8 bits.• Any MAC monitor can

display 32 bit PICT files

PICT FormatPICT Format• MAC system

format used to exchange data via clipboard.

GIF FormatGIF Format• Graphics Interchange

Format.

• Created by Compuserve to speed downloading of graphics.

• Limited to 256 colors.

• Compression format

GIF FormatGIF Format• Can be both

interlaced and non-interlaced

• Common Internet file format– 87– 89a (interlaced,

with one transparent color)

PNG FormatPNG Format• Portable Network

Graphics• New format targeted

for Internet use• Can support up to 48

bit color• Big compression

factor• Can support multiple

transparent colors

PSD FormatPSD Format• Photoshop native file

format.

• Supports all image types from line art to photos.

• Increasing compatibility with other software.

PSD FormatPSD Format• PSD can hold an

infinite amount of channels!

• Each layer can hold 24 channels.

• Infinite amount of layers are possible.

• Subject to available RAM!!!!

Multi-Channel to .GIFMulti-Channel to .GIF

Photoshop RGB

Indexed 256

.GIF

Convert to:

Save as:

PCX FormatPCX Format• From ZSoft Corp.• Many versions

exist.• Great for indexed,

grayscale and line art.

• Supports only one channel.

PCX FormatPCX Format• Photoshop only

supports PCX version 5!

• Convert .pcx to RGB to use most Photoshop tools.

• PC Paintbrush format.

Kodak Photo CD - PCDKodak Photo CD - PCD• Kodak format for

images stored on Kodak Photo CD.

• Uses YCC color model.

• Limited to five image sizes.

Kodak Photo CD - PCDKodak Photo CD - PCD• Photoshop

opens as a LAB color model.

• Photoshop can not save as a PhotoCD format.

Bitmapped FormatsBitmapped FormatsAnd PixelsAnd Pixels

Vector FormatsVector Formats• Images are a series

of pixels that are "turned on" based on a mathematical formula.

2(x + y)z

Vector FormatsVector Formats• Vector Formats are

basically defined by shapes and lines

• No more than 256 colors

• Clip Art

Vector FormatsVector Formats• Not resolution

dependent

• Infinitely scalable

• Not appropriate for photo realistic

• images

Common Vector File Common Vector File FormatsFormats

• WMF

• AI

• Post Script

• CGM

• Fonts

• DRW

• CIL

WMF FormatWMF Format• Windows Metafile

Format.

• Designed for easy exchange between Windows programs via clipboard.

• Common clipart format.

PostScript FormatPostScript Format• Developed by

Adobe Systems for typefaces.

• Expanded for many graphic elements.

• Encapsulated Post Script (.eps) is of this format.

PDF FormatPDF Format• Adobe Acrobat

file format.

• Portable Document Format

PDF FormatPDF Format• Integrates color,

graphics and text

• Searchable format

CGM FormatCGM Format• Computer Graphics

Metafile

• Most common DOS-based format

• Used by -– Harvard Graphics– Freelance Graphics– Others

CGM FormatCGM Format• Older versions of

format may not load cleanly into modern versions of software

• Can support very elaborate graphics

• A "schizophrenic" file format!

Vector FormatsVector FormatsAnd ShapesAnd Shapes

Software ChoicesSoftware Choices• Traditionally,

different software creates either bitmapped or vector art

• This is changing!

Software ChoicesSoftware Choices• For bitmapped,

names that include the words “Paint” or “Photo” indicates that the primary function of the software is to create and manipulate bitmapped formats

Software ChoicesSoftware Choices• For bitmapped,

names that include the words “Paint” or “Photo” indicates that the primary function of the software is to create and manipulate bitmapped formats

• Examples –– Adobe Photoshop– Deluxe Paint– Photoshop Elements– Macromedia Fireworks– Corel Photo-Paint– Paint Shop Pro

Software ChoicesSoftware Choices• For vector art,

names that include the words “Draw” or “Illustrator” indicates that the primary function of the software is to create and manipulate bitmapped formats

Software ChoicesSoftware Choices• For vector art,

names that include the words “Draw” or “Illustrator” indicates that the primary function of the software is to create and manipulate bitmapped formats

• Examples –– Adobe Illustrator – Corel DRAW– Microsoft Draw– Macromedia Freehand– Serif DrawPlus– Macromedia Flash

Software ChoicesSoftware Choices• Most modern

versions of bitmapped software also include draw tools

• Photoshop 6.0 now can create vector art.

Software ChoicesSoftware Choices• Adobe Acrobat,

desktop publishing, etc. software is friendly to both categories of graphic types

When to Use What When to Use What and When!?!? and When!?!?

What are the requirements of your output device?

When to Use What When to Use What and When!?!? and When!?!?

Image Quality File Size

When to Use What When to Use What and When!?!? and When!?!?

Image Quality File Size

Photo Image

Illustration

When to Use What When to Use What and When!?!? and When!?!?

Image Quality File Size

Photo Image

Illustration

Internet

Other ComputerDevices

Curriculum Content andCurriculum Content and

Activities created byActivities created by

Dr. Mark MortensenDr. Mark Mortensen

Dept. of Technology & Dept. of Technology & CognitionCognition

University of North TexasUniversity of North Texas