Raster and Vector Images – What’s the Difference?

Have you ever been confused in knowing which file format to submit to your graphic designer or printer? Maybe you would just like to know why they’re so picky with what you submit! Isn’t one large-scale, high resolution document all you will ever need? I’m afraid the answer is no. Many people, including some of our clients here at Eyedeal Graphics, run into these questions and are in need of clarification set in simple terms. We are here to help!

The questions come from the common misconception between raster (also known as bitmap) and vector file formats. The simple answer is a raster image has limited usage because of it’s multi-element structure while a vector image has no limits because it is one individual element. Are you interested in a deeper explanation? If so, keep reading!

Most of us are likely more accustomed to using raster images since they are the format of all photographs. A raster image is made of pixels, where there are single elements or points of color in a display monitor or printed material. When zoomed in, these pixels can be seen as small squares. Raster images are resolution dependent, meaning the quality of the image can be altered when displayed at different sizes.

Vector images are the opposite of raster where instead of multiple pixels they are displayed by geometric primitives defined by mathematical formulas. For example, a solid line in a raster image consists of thousands of pixels while a vector line is one single element. A vector image is not resolution dependent and can be resized without losing quality. (Keep in mind that resolution capacity may change depending on which output device is rendering them) One of the most common uses of vectors is for logos as it is extremely important for a logo to have the capabilities of resizing and saving for multiple digital and print uses without losing quality.

Below is an overview of the differences between raster and vector images. Revert to this list whenever you are challenged with choosing a specific way to create your art or submit your image files.

Raster:

  • Displayed with pixels or small, single elements combined to compose a final image.
  • Resolution dependent.
  • Require original size for best resolution.
  • Are non-line art images – typically include complex compositions such as chromatic gradations and undefined shapes or lines.
  • Less economical and can be more difficult to work with. However raster is still best used for images with complex structure like photographs.
  • Measured in ppi, pixels per inch. (or dpi/dots per inch for print) For example, 300 ppi is high resolution for creating a print file.
  • Commonly used for Photographs, simple web graphics, image effects, and complex color images.
  • High resolution images should only be used if your equipment has the capability to display in high quality.
  • Raster images can be viewed as “painted” because the compiling of pixels to create a final complete image. This is similar to the way a painting is composed.
  • Common raster formats include TIFF, JPEG, GIF, PNG and BMP files.

Vector:

  • Displayed by geometric primitives defined by mathematical formulas.
  • Not resolution dependent. (the rendering of your output device will determine display resolution)
  • Quickly and perfectly scalable – There is no upper or lower limit for sizing vector images.
  • Are line-art images that do not include effects and are solid colors.
  • Are more flexible to work with and tend to be considerably smaller in file size than their raster counterparts since they don’t have to read and memorize thousands of tiny pixels.
  • Over time vector graphics will likely surpass raster graphics in both prevalence and popularity.
  • Commonly used for logos, illustrations, technical drawings, engineering, and software that requires vector format such as some printers, etching, engraving, etc. Also used in CAD and 3D graphics.
  • Adobe Illustrator is an example of a vector program that has the ability to create color gradients within one single shape, but these are actually raster effects. However, the gradient can still be scaled to any size because pixels are being added or taken away rather than resized.
  • Vectors can be viewed as “drawn” because of their solid lines, simple colors, and simple editing. This is similar to the way solid, single strokes are found in a drawing.
  • Common vector formats include AI, EPS, SVG, and sometimes PDF.

In conclusion, there is a time and place to use both of these image formats. Hopefully you found these tips helpful and gained a better understanding of how they differ from each other. With your new understanding of these two terms, you will never have to re-submit your files again! As always, feel free to reach out to Eyedeal Graphics with any questions or to get started on your next design project!