Illustrator — Vector-based files' advantages over raster-based files

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Vector-based and Raster-based programs.

This page is required reading for beginners and, whilst this page has quite a lot of text (and not very many images), the information contained on this page forms a crucial building block to understanding Adobe Illustrator.
Please take time to give this page a good a read!

 

Adobe Illustrator is a Vector-based program

One of the most important things to understand about Adobe Illustrator is the difference between Vector-based images and raster-based images. Illustrator is a Vector-based program, and this simple fact is something that makes Adobe Illustrator unique.

Text, images, logos and artwork that are produced on a Vector program are created by using mathematical equations. These equations place important reference points on the page, and then place straight and curved lines between those reference points.

If you examine the image on the right, you will see that there are many light-blue reference points, and there are some curved and straight lines between those reference points.

The reference points, lines and curves are, in fact, an outline, and the Vector program then uses just a few lines of computer code to fill in that outline. In the image on the right, the few lines of computer code will simply say "white".

 

Raster-based programs

Raster-based programs (e.g.: Adobe Photoshop) create images by using pixels (i.e.: dots). Each and every pixel (i.e.: dot) must be created individually, and each and every pixel (i.e.: dot) must be stored on your computer. If you want document that measures 90mm x 55mm (e.g.: a business card), has a red background and some white text, then each red or white pixel (i.e.: dot) would need to be created and stored on your PC; and, the file will need to have 690,526 individual pixels (i.e.: 690,526 individual dots).

 

Vector-based and raster-based programs compared

Enlarging images

Vector-based files can be easily enlarged, and not lose any of the quality. Raster-based files, however, do not enlarge very well. In fact, raster-based files always loose quality when they are enlarged.

Enlarging images — Vector-based files

The fact that  Adobe Illustrator is Vector-based means that Illustrator has one fabulous feature — if you enlarge the image, then you will not lose any quality in the image — the image will remain crisp and clear, even if it is enlarged to the size of the Earth.

The reason Vector-based files can be increased in size, and still retain a high quality image, is because the mathematical equation remains much the same, with just the numbers altering. So, the outline can be easily increased in size, and then a few lines of computer code will simply colour in the image (in the above image, the few lines of computer code simply said "white").

You do not need to understand the mathematics that create this outstanding characteristic in Illustrator; all you need do is understand that the mathematics works, and it means that you can increase the size on any image, and there will not be any loss in the quality.

Enlarghing images — Rastor-based files

Raster-based files, however, do loose quality when they are enlarged.

The previously mentioned 55mm x 90mm file created in a raster-based program resulted in 690,526 individual pixels (i.e.: 690,526 individual dots) being created. Well, if you enlarge that file, you will always have the same number of pixels. So, if the image was increased in size to 550mm x 900mm, then:

  • The file would need to have 69,050,638 pixels to create a crisp and clear image; however
  • The now enlarged file would still have the same number of pixels that it had before it was enlarged (i.e.: 690,526 individual pixels).

The enlarged image would appear bitmapped (or pixilated), and this will occur because there are not enough pixels (i.e.: dots).

Consider the two below images.

  • The left-hand image was created on a vector-based program (i.e.: Illustrator). It was enlarged 4.167 times, and the text remains at a high-resolution 300 dots per inch — Illustrator's mathematical program did all the work.
  • The right-hand image was created in a rastor-based program (i.e.: Photoshop). The image was enlarged 4.167 times, and the effective resolution dropped down to only 72 dots per inch.

               

So, the resolution of the text also effects the quality of the text on a file.

 

File sizes

The size of a file can create problems. Large files take up more computer space, large files slow down your computer, and large files can be difficult (or even impossible) to send to your commercial printing company over the internet.

File sizes — Vector-base files

Illustrator's Vector-based files offer a second advantage — they are quite small.

Everything in an Illustrator file is created by mathematics (and a few lines of computer code), and the size of the file remains much the same no matter how big the finished document will be. For instance, a 5 meter x 5 meter sign that has a red background and some white text could be created on a file that was a small as one (1) megabyte — the finished document might be massive, but the file used to create that massive document can be quite small (i.e.: just a few mathmatical equations).

File sizes — Rastor-base files

Given each pixel on a raster-based file must be created individually, the computor space required can be substantial.

  • The above-mentioned 55mm x 90 mm business card could take up as much as 2.3 megabytes.
  • Imagine, however, that you want to create a sign that measures 5 meters x 5 meters, had a red background, and some white text. The file could easy end up taking up 13 or 14 gigabytes of space on your computer, and imagine trying to send that file to your printing company over the Internet!

 

Editing

Vector-based files can be easily edited.

Raster-based files, however, can be hard to edit.

 

Conclusion

If you are a beginner, and you have a choice between learning Illustrator (a vector-based program), or learning a raster-based program (e.g.: Photoshop), then consider learning Illustrator for the following reasons:

  1. Illustrator's vector-based files are smaller than the raster-based files, so Illustrator's files are easier to send to people.
  2. Illustrator's vector-based files are scalable (i.e.: they can be enlarged without any loss of quality), whereas raster-based files are not scalable (i.e.: raster-based files cannot be enlarged and maintain quality).
  3. Illustrator's vector-based files are easily edited, whereas raster-based files are not easily edited.