BY: Colleen Jolly
All digital imagery can be categorized into two main types: vector and raster. Vector images are resolution independent whereas raster images are resolution dependent. Resolution then, is the quality of your image and is often referred to in dots per inch (DPI) or pixels per inch (PPI). All computer monitors are based of the small rectangular cells known as pixels.

Vector images are created based on mathematical equations and can be scaled up or down to any size without losing the crispness of the image quality. Vector graphics software uses the algorithms to create the best possible image based on the screen resolution of your monitor. Raster images are stored pixels that do not change when you scale them, their size and quality is set and is not relative to your screen resolution.

Vector graphics require specialized software to open and edit such as Adobe Illustrator or Macromedia Freehand. These vector images can be exported in several common raster file formats to then be placed in documents or presentations. Raster images require special software to edit or modify such as Adobe Photoshop but do not require special software to view with most being viewable in the MS Office Suite or any web-browser.

Vector

o  Typically small file size

o  Often, but not always more visually simplistic in nature

o  Most common use: logos

o  Need special software to view

Raster

o  File size dependant on the image quality (resolution) and physical size

o  Photorealistic and visually rich

o  Most common use: photos

o  Do not need special software to view

Most proposal graphics specialists use a combination of vector and raster pieces to create covers and other graphical items and typically export a raster file to insert into a Word or PowerPoint file to complete the proposal.

There are several raster file formats that are appropriate for use in proposals. When considering a file format you must first consider if your client has specified one (which is not common but does happen) and then you must consider your file size limitations, particularly if you are emailing or otherwise electronically delivering the document.

JPG and PNG files at 150-200dpi are the smallest byte-sized formats that print crisply with high quality. TIFF is another high-quality format but tends to bloat documents with regards to file size. GIF files are well suited for online imagery and not for printed documents, although they can be inserted into PowerPoint and used as animated GIFs. While many people claim success with various Windows MetaFile formats, I do not typically recommend those.