There are two basic kinds of graphics; those whose structures are based on pixels, and those based on mathematical formulas.  I have placed commonly used graphic terms under their particular type:
 
 

Math-Based Graphics:  Applications that draw shapes with handles on them are object-oriented, or vector, programs.  They usually have the word "draw" or "illustrate" in the name.  You can select an object, or grab its handle and change the object's size or shape.
 

Images from Scanning

Images obtained from a scanner are always bitmapped or rasterized (made of pixels).   Though there are many bitmapped file types (GIF, JPEG, PNG, BMP, PCX, PCT, PIC, TIFF) to which a scanned image can be saved, the two most commonly used (because they are used on the Web) are GIF and JPEG.
 

GIF:  Graphics Interchange Format

• Indexed Color - 8 bit color  (maximum of 256 colors)
• Transparency: one color in the image can be made transparent (in a graphic editing program)
• Interlacing = layered (downloads appear gradually)
• Can be animated
• File size is larger compared to the same image saved as a JPEG.  GIF files grow in size as the number of colors increases.

• Best used for images with large areas of color, such as simple illustrations, logos, text as graphics, cartoons, etc.
• Use with an image of 256 colors or less
• Use when you need the sharpest possible image (especially with line drawings or maps).  The GIF compression scheme packs an image down much less than a JPEG does, thus allowing the file to be reconstituted much better.
• Use when you want to animate your graphic
• Use when you need a transparent image
• Use for photographs if your image is less than 1.5  inches across (usually a "thumbnail" picture). The quality at this size is the same as a JPEG and the file size is smaller.

 

• 24 bit color (16.7 million colors)
• Not transparent
• Not- interlaced: (picture downloads from top to bottom in full resolution)
• Can not animate
• Multiple compression levels
• File size is smaller compared to the same image saved as a GIF.  JPEG files always use 24 bit color and are compressed by discarding some information.

• Best used for images that require subtle transitions between colors such as photographs, watercolor images, pencil or charcoal drawings.
• Use when your image exceeds 256 colors and the colors have subtle variations

A Glossary of File Formats

BMP  BMP is the standard Microsoft Windows bitmap format.

EPS  The Encapsulated PostScript (EPS) language file format is supported by most illustration and page-layout programs.

FPX  The FlashPix (FPX) file format, developed by Kodak, is designed to speed the transfer and display of large, high-resolution files in applications that support the FlashPix technology. The FlashPix format supports JPEG compression, grayscale, and RGB color modes.

GIF  The Graphics Interchange Format (GIF) was originally developed by CompuServ for exchanging images over its online service.  It is commonly used to display graphics in Hypertext Markup Language (HTML) documents over the World Wide Web and for transferring photos over the Web and other online services.

JPEG  The JPEG format is frequently used for transferring photos electronically. An abbreviation for Joint Photographic Experts Group, JPEG compression economizes on the way picture information is stored and identifies and deletes extra information not essential to the display of the photo. Depending on the level of compression, however, this loss of information may not be noticeable. JPEG photos are automatically decompressed when they are opened.

PCX  PCX format, created by ZSoft for its PC Paintbrush software, is commonly used by IBM PC-compatible computers. If colors appear incorrect when you open a PCX file, the file was probably made using older software using a previous version of the PCX format.

PDF (Adobe Acrobat)  Portable Document Format (PDF) files retain all the graphics, formatting, and fonts of the original document and can be opened and printed by anyone with a MacOS, Windows, UNIX, or DOS Acrobat viewer, regardless of whether the original application or fonts are on the computer where the file is viewed. In addition, Adobe Acrobat format compresses the data so that the file is much smaller than in other formats. When using this format, text in your photo is converted to bitmap format and is made part of the photo.

PICT  The PICT format is widely used among MacOS graphics and page-layout applications as an intermediary file format to transfer documents between applications.

PNG  The PNG format was developed as an alternative to the GIF format and, like GIF, is used for displaying images on the World Wide Web and other online services. PNG preserves all color information and alpha channels in an image and uses a lossless compression scheme to reduce file size.  When saving an image in PNG format, you can choose to display the image in gradually increasing detail as it is downloaded.

PSD (Photoshop)  When you save to this format, all layers are preserved except the Text layer. Text is converted to bitmap format and is made part of the layer immediately below, so you will not be able to edit the text again after it is saved in Photoshop format.

TIFF  The TIFF format is used in desktop publishing and for exchanging pictures between computer platforms (such as Windows and MacOS).  TIFF was originally developed specifically for saving scanned documents from any operating system and can, therefore, be read by either Windows or Mac systems.
 
 
 

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