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.
>>
>
>