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View Full Version : vector vs. bitmap whats the difference?


cbritton
November 26th, 2001, 01:45 AM
Ok bitmap works with pixels I am told and vectors work with shapes. So when would you want to use one over the other? I mean for webpages wouldn't you want to use something like photoshop over illustrator. But for instance when would you want to use Illustrator? This whole vector and bitmap thing has me confused. What can one do that the other can't?

Buzz
November 26th, 2001, 06:10 PM
Everything, and I mean everything, you see on a monitor is Raster (bitmap). Vector and Raster generally refers to how the image information is output to an imagesetter or printer.

Basically raster images have a set limit of pixels. they can not go above that limit. The limit is set when the image is created. Increasing the size of the raster image beyond it's pixels results in what is commonly referred to a "Broken Pixels." These are the results that show the pixels or degrade the image to a point where pixels are noticable visible when they are not supposed to be.

Vector images are based on math. They have no set limit of pixels. the pixel limit can change easily because the mathmatical equations are simply recalculated upon output.

Currently there are only 2 web formats that support vector objects, SWF (Flash) and SVG. SVG is far more rare than SWF. You can see the benefit of web vectors in any Flash sequence. It scales to fit the window size. it doesn't get broken up or lose clarity. The same holds true for print. Vectors are generally cleaner, clearer images.

Not all images can be vector objects. Generally all photographs are raster images.

As for the use of Illustrator for the web......

<RANT>
I think it's bogus. There's no need for it. Adobe is just after the $$$$$s. Illustrator has been a staple of the print industry for years and years, but (and this may come as a shock to some) most of the print industry is still using version 8 (Illustrator is currently at v10). Why, you ask? Because with v9 and v10 Adobe added all the nifty RGB/Web features to Illustrator. What this did is slow the application down considerably and make it far less reliable than version 8. The print industry has been screaming at Adobe since the release of v9. There were high hopes that v10 would correct some of the problems with v9 and it did, but now it appears others have cropped up. Adobe is not toroughly testing Illustrator. They are trying to keep up with competitors. AI10 was released just so Adobe could have a native OSX application to compete with Freehand. Adobe also appears to be moving in the direction of an all-in-one application which has shades of CorelDraw to it. This, I feel, is another mistake. To sum it all up, if you are doing web design/layout and you are familiar with Photoshop (especially v6.0.1) there is no need for Illustrator unless you are creating Flash content. Photoshop 6.0.1 has vector tools.
</RANT>

Eggles
December 9th, 2001, 01:55 PM
Buzz - I agree that Illustrator is generally not required for web work. HOWEVER, there are times when graphics destined for web pages are best created in Illustrator first, then rasterised in Photoshop for implementation (usually as a gif) on a website. I am thinking in terms of graphics such as logos and maps which are far better drawn (and more easily) originally in Illustrator.

cbritton - I hope this helps clarify when you would use one file format over the other. There are just certain times that graphics are more readily produced in a vector program such as Illustrator or Freehand, but you still must convert it to a raster format for display on the web (at least if it is a static graphic), as the web currently doesn't allow for vector graphics, except as Buzz has pointed out, in Flash files and whatever the svg file format is.

Buzz
December 9th, 2001, 11:35 PM
Agreed Eggles. But there is no need for vector logos if the logo is NEVER going to a printing press. Of course, that is extremely rare.

SVG = Scalable Vector Graphics. An Adobe proprietary format designed to be used instead of the SWF format. Like all web formats, Macromedia's SWF is a bit better.