Both files above started out the exact same size (1" x 2.5"). For demonstration purposes, I enlarged both by 200% to show the differences.

As you can see a raster based image at 72 dpi has fairly jagged edges. When increasing the size to 200% the resolution drops to 36 dpi and it is really jagged. On the other hand a vector based image looks much less jagged since the curves are defined mathematically and resizing the image has no effect on quality.

Raster images are the most frequent file types (jpg, bmp, gif) seen in every day use and have a continuous tone like you see in photographs. These file types are used in digital cameras, most graphic programs, clip art, web graphics, and those files we have all seen passed around in email with funny images.

A computer screen generally displays 72 pixels per inch and most printers work with 600-2400 pixels per inch. The terms ppi, pixels/inch, dpi, dots/inch and spi, samples/inch all are different terms for describing how the grid is laid out which is it's resolution. The only difference between the terms are the devices being used. Scanners and monitors generally use ppi or spi. Output devices use dpi or lpi. Lpi is lines per inch which we will talk about in the future.

Drawing programs like Corel, Freehand, and Illustrator are vector based which is very different. They use math to describe the shapes that make up an image. The advantage of using math to describe a shape is it doesn't have a set resolution. The shape will display/print at the highest resolution the output device supports. This is very different then raster images which have a fixed resolution. Also fonts and therefore text is usually vector based.

Raster images are perfect for web graphics and document creation but they are not useable for screen printing. Gif file extensions are the worst and will not be accepted even for re-draw. Gif's just do not retain enough information for a clean image to be pulled out.

Raster files keep all the colors in a flat file where as vector files have the colors in separate layers. In screen printing, the colors in a design have to be broken out on separate layers so that screens can be created. 1 color = 1 screen, 5 colors = 5 screens.

For screen printing, we will need to re-create all images provided in a raster format to a vector image. We have skilled artists on staff that will work with you to re-create your logo.

Some links that further clarify the differences:

http://www.sketchpad.net/basics1.htm

http://www.signindustry.com/computers/articles/2004-11-30-DASvector_v_raster.php3

The good news is that for embroidery and digital printing, raster images can be used.

For embroidery, we must recreate the file (digitize) so that the embroidery machines know how to sew it. The digitized file tells the machines things like where to punch, how far to travel, spacing between needle punches, etc.

For digital printing, the raster image would need to be sent to us in the print size you require. Digital printing uses a CMYK process that allows us to print the color tones and gradients much like the printer sitting on your desk.

We look forward to working with you on your project. Please let us know if you have any questions.