Wednesday, September 12, 2012

Raster Vs Vector Graphics

The Tuesday Tutorial, one day late.


Raster graphics, also known as bitmap graphics, are made from points of color called pixels.

Raster graphics are resolution dependent – this means it cannot be scaled larger without losing quality.

The standard resolution of a screen image, the images you see on the Internet, is 72 pixels per inch or ppi. Meaning there are 72 individual points of color in each inch of your image.

The standard printing resolution is 300 dots per inch or dpi. PPI and DPI are the same thing because a pixel is the electronic version of a printed dot. I will always default to dpi because I work in the print world.

If you tried to get 72 points of color to make the same image as 300 points of color you wouldn’t get too far. The image would be blurry or pixelated, which means the images is jagged because can see each individual point of color instead of a smooth line. In the print world 72 dpi is considered low resolution or low rez and 300 dpi is considered high resolution or hi rez.


There is no resolution in vector graphics because they do not use pixels, they use the dreaded MATH. Computer software that creates vector graphics, like Adobe Illustrator or Silhouette Studio, relies on a mathematical formula to create lines. A single vector is a line, either straight or arced between two points.

Vector images can be scaled without losing quality so vector based programs like Adobe Illustrator are used to create logos. They can be scaled down for business cards and blown up for billboards.

The Silhouette studio operates at a resolution of 72 dpi. If you import something that is hi res into a low res environment or document it will come in HUGE, 417% larger than you expected to be exact, because there are so many pixels. On the other hand a low res images that is added into a high res document will be a tiny 24% of its original size because there are so few pixels.

The Silhouette Studio software uses vector graphics because just like you can’t cut a dot, the Silhouette can’t cut a pixel. If you import an image into the Silhouette Studio software for a print and cut you will need to use the trace tool to create cut lines.

So what have we learned today? 

Pixels are points of color that can be printed but not cut. High resolution images are for printing, low resolution images are for the web. Vector images use the dreaded MATH to create lines that can be printed on a printer and cut with the Silhouette. Vector images can be scaled up or down without losing quality.

Hopefully you have a better understand of the difference between raster and vector images and when and how they are used. If you have any questions post them on the blog or on YouTube. I will respond to them not only on the blog or YouTube but also in your email box if it’s included because I don’t like to have to go back and look for the answers to my questions and I doubt you do either.

Happy Crafting,

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