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I should also remark that vector information and raster information may exist in the same PDF file. For example, a PDF of a magazine or newspaper will probably vector text and column borders while photography will be raster at ~300dpi. On Thu, Apr 28, 2011 at 2:58 PM, Carl Wiedemann <[log in to unmask]>wrote: > Generally PDFs are capable of displaying two types of information: Vector > and Raster. > > Vector information is composed of lossless data that describes points, > smooth lines, gradients, and curves. Vector information is lossless and has > no native resolution, it can be infinitely scaled. Text data is understood > as vector information if we were to regard textual documents as images. > Generally, when composing a document in a word processor and printing it to > a PDF results in the text as actual vector shapes -- you can zoom-in on the > text as much as you'd like. PDF readers understand this information as > native text you can select the text with a cursor, search the text, and > copy/paste. Other formats like SVG and ESP generally express vector > information. > > Raster information is composed of pixels. JPEG, PNG, GIF, BMP, TIFF are > examples of raster information. These have a definite resolution, and, from > a computing perspective, are just a bunch of dots. When you scan an image > (or a document), it is digitally translated a raster. Digital photographs > are raster. There are some techniques using Optical Character Recognition > (OCR) which can actually recognize characters in a raster image and > transform them into text data. There are also procedures to do a "bitmap > trace" to attempt to create vector information from a raster image. > > More info here > http://en.wikipedia.org/wiki/Vector_graphics > http://en.wikipedia.org/wiki/Raster_graphics > > > > > On Thu, Apr 28, 2011 at 11:10 AM, Van Mil, James (vanmiljf) < > [log in to unmask]> wrote: > >> I often employ the word 'raster', along with some other foul language, for >> any PDFs that don't have manipulate-able text. >> >> -James >> >> -----Original Message----- >> From: Code for Libraries [mailto:[log in to unmask]] On Behalf Of >> Keith Jenkins >> Sent: Thursday, April 28, 2011 1:06 PM >> To: [log in to unmask] >> Subject: Re: [CODE4LIB] What's the descriptive technical terminology?... >> pdf image of a page. pdf format used with cut paste. >> >> I've also heard many people use the term "searchable PDF" for a text-based >> PDF. >> >> Keith >> >> >> On Thu, Apr 28, 2011 at 12:43 PM, Peter Murray <[log in to unmask]> >> wrote: >> > That is the same terminology I use as well -- image-based versus >> text-based. I find that works most times because people can visually see if >> something looks like a scanned image. >> > >