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					     Vector vs. Raster




What’s the difference between vector and raster file
formats?

The real difference between the two formats is how
they are used.



                http://www.logoshed.net/store/docs/8/raster_vs_vector/
Raster artwork
(also known as bitmaps):
 are composed of lots of small dots. This lends itself to photographic or artistic effects because
  color gradations can be made very smooth in a bitmap format. However, bitmap images lose their
  clarity when they are increased in size because the dots get bigger. Take an image that's 10 pixels
  wide by 10 pixels high, stretch it to 100 x 100 pixels and it looks like it's made of big squares.
 Adobe Photoshop, the industry standard for digital photo editing, allows users to open and edit




 File Formats                              :

 •Graphic Interchange Format (.GIF)

 •Joint Photographers Expert Group (.JPEG, .JPG)

 •Tagged Image File Format (.TIFF, .TIF)

 •Encapuslated PostScript (.EPS)*
Vector artwork
(sometimes called line art)
this kind of artwork is made up of lines and filled areas only, which are mathematically
 drawn and calculated (hence the term vector) by the software you use. They can be stretched
 in size without losing any clarity or sharpness. Because of their mathematical origins, vector
 images are readily scalable without distortion.

For vector image editing, use either Adobe Illustrator or Macromedia Freehand. Either
 program will also allow users to import raster images into their vector files.


File Formats:
 •Illustrator (.AI)*
 •Encapuslated PostScript (.EPS)*
 •PostScript (.PS)*
 •Windows Meta File (.WMF)
 •Flash Movie (.FLA, .SWF)**



 * Both Illustrator AI and EPS formats allow users to place raster images within a vector file.
 The raster image is not converted to vector format; rather it is simply embedded in the vector
 file, and is rendered in raster format.
                      Vector/Raster
                      When and Why?
Vector programs
make short work of     If you are working with mainly solid color objects,
manipulated text
and any solid color
                        manipulated text or many small objects, the clear
work.                   answer is that a VECTOR program will save you
                        time.

                       If you are working with complicated drop shadows,
                        or other 3D effects, texture or photographs, RASTER
                        is the correct choice.


For photo work,
only a raster
program makes
sense.

                                          http://www.webreference.com/graphics/column31/4.html
TIFF to the rescue
 Many times vector programs do not have the
  power to rasterize images with good results

 TIF is a raster program, widely used in print
  work, that supports 24 bit color without
  degrading quality. You can expect better
  results with this format than with
                                                       Exported directly to 72 dpi JPG
  uncompressed JPG files.

 Export as TIF and then open in a raster
  program to convert to GIF or JPG.




                                    Exported at 300 dpi in TIFF format. Opened in
                                    Photoshop to reduce resolution and optimize: 9.63kb
Going the other way - TRACE
When you have learned to work well with a vector program, and are
comfortable drawing and editing nodes in paths, you can import the
raster image and place it on its own layer.
  1. Reduce the opacity of the layer to fade the image back (if
     available), or draw a semitransparent white rectangle over the
     image.
  2. Lock the layer containing the image to be traced.
  3. Trace the objects on a new layer.

                                 Tracing partially completed. The blue
                                 outline shows one area that has been
                                 traced – this area is now a vector object.



Note: Incorporate the raster image into the vector image if you are not going to
need to resize the image.

				
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posted:7/30/2012
language:English
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