Raster (Bitmap) Vs. Vector
By Nicholas Svizzero
The two main types of image files that designers need to account for are Raster (Bitmap) and Vector files. However, each type of file has certain strengths and weaknesses, and designers need to know how to account for both.
Raster (Bitmap) & Vector Defined
Raster art include photos captured by cameras or scanners in addition to documents created with pixel-based editing programs such as Adobe Photoshop. When using these types of programs, the artwork created could be akin to “painting” as the edges of color bleed into one another and don’t create a hard edge. This allows for smooth transitions of color.
Vector art is created using vector illustration software programs, such as Adobe Illustrator. These programs use mathematic equations and geometric primitives (points, lines, and shapes) to create art that is clean and can be scaled infinitely.
Pixel Vs. Vector
A pixel, of which raster images are comprised of, is a single point (the smallest element) in a display device. If you were to continually zoom in on an image (photo, bitmap, etc.) you would begin to see tiny squares (pixels). The maximum and minimum resolution is set by these pixels – and as a result, must be manually set to the correct size prior to being sent to print as enlarging would lose and degrade quality. The two factors that determine this are document dimension and pixels per inch. Here are some common ppi (pixels per inch) resolution required by printers:
300ppi – Standard Paper
240 ppi – Shirt Printing
20 ppi to 200 ppi – Large Format Printing (Size Dependent)
Vectors, as mentioned above, are mathematical calculations from one point to another that form lines and shapes. If you were to zoom in on these types of files, no pixels (squares) will show up and it will always look the same. The main two benefits of vector graphics are as follows:
Due to being resolution independent, vector shapes (called objects) can be scaled and printed at any size without degradation of any sorts. The highest resolution this can hit is the highest resolution that the printer allows.
2. Color Editing
Due to non-bleeding and properly defined cuts, editing colors is extremely simple. This is very important when determining how many colors is allotted for printing to ensure proper cost-management, as adding additional colors can dramatically increase costs and having to reduce back colors would provide an ill-advised proof.
Example: Should A Logo Be Raster or Vector?
In today’s business world, without a doubt a logo should be created as a vector. The scalability this allows for a company to have and implement (examples include print, web and mobile devices) would be crucial to agility and allow deployment to go by so much faster. However, you would be surprised at how often companies come to you with raster graphics (common types include jpg, gif, tif, bmp, psd, eps and pdfs originating from raster programs) without the original vector images. It is up to designers to use these raster images to create vector images in order to provide materials with the highest possible printable quality – which can be accomplished in a multitude of different ways.