There are two types of images that your laser engraver will work with – raster images or vector images. The two are just different types of computer graphics. So, what is the difference between the two? And which one is better?
Is raster or vector better?
Vector images are typically more versatile and flexible than raster images. Working with vector images is a lot easier e.g. you can easily resize it to any size you so wish without pixelating it – there is no upper or lower limit. Vector images are therefore a more popular option.
Engraving using a raster image
A raster image, also commonly known as a bitmap image, is comprised of millions of tiny squares which are called pixels. If you zoom into the image, you will be able to see each pixel’s square outline. You can especially see the pixels around the edges of the image because of the significant color contrasts.
So how does a laser engraver work with raster images? The best analogy would be the ink-jet printer which prints line by line. Raster image laser engraving works almost the same way.
- The computer-generated bitmap image made of pixels is interpreted by the laser engraving machine’s CNC controller.
- The laser keeps swiping back and forth across the area where it is working.
- The laser engraver uses the laser in an on-off pattern to individually engrave each pixel into the base material of the workpiece. It is a bi-directional process in which engraving is done in an alternating manner in both directions.
During the line by line engraving process, both axles run with different speed. The speed of the X axle (the axle where the laser-head is attached) is always higher than the Y-axle. The PPI (Pulses Per Inch) also plays a crucial role as it controls the density of the laser points.
Since it engraves one pixel at a time, raster engraving is somewhat slow.
Engraving using vector images
Vector images are made of thin lines and curves which are known as paths. Each path is rooted with a mathematical formula that determines the shape, as well as the fill and border colors.
Vector image engraving is also known as “Scoring.” The CNC controller uses the series of linear X-axis and Y-axis locations and directions for the laser to point based on the image generated by the computer. The laser keeps following the instructions given by the computer and engraves the piece smoothly.
Once the file is imported from a graphics software, the outline is marked for vector engraving. The laser traces the image vector by vector and engraves it on the material. The axles move slowly but simultaneously to achieve a smooth engraving. Vector engraving works the same as laser cutting except for the power settings. If you use a low power setting, you will get an engraved image but if you use a high-power setting, you will get a laser cut.
Vector engraving is perfect for flat materials and since it engraves in a continuous manner, the vector engraving is less time consuming than raster engraving.
The Appearance of Vector Engraving vs Raster Engraving
When it comes to appearance, vector engraving looks much finer than raster engraving because raster engraving is just one line thick. Vector engraving is used where finer details are required which is not possible with raster engraving. Vector engraving is therefore perfect for small items like jewelry and other decorative items.
Raster engraving, on the other hand, works perfectly for art-works that come with bolder appearance. The raster engraved artworks look more like 3D objects as the engraved areas are crafted on materials like wood.
Raster or vector – which one should you use?
When to Use Vector Engraving:
If you want to cut or engrave a 2D image on a flat surface, vector images would be the most ideal. Also, think of your desired end product – if you want to achieve an image that only has lines, vector engraving will be perfect.
Examples of items to make with vector engraving
- Different types of business signages
- Bookmarks and many other small 2D decors and mementos
- Jewelry, pendent and ear-rings engravings
The most commonly used materials for vector engraving are metal, wood, cork, paper and plastic.
When to Use Raster Engraving?
If you are looking to achieve a 3D image, then you should go with raster images. Raster engraving works well with designs that require different depths of engraving. With raster engraving, you can engrave precise and intricate details onto your material. This is in fact the main reason why raster engraving is more time
Examples of raster engravings projects
- Corporate photo plaques
- Engraved photo plaques which are used for gifting purposes
- Artsy home décor items
Raster engraving is mainly used on softer materials like wood and leather.
As we have seen, vector and raster images both serve distinct purposes so the choice of the best one to use will depend on what you are trying to achieve. But as a rule of thumb, use vector images for 2D image engravings and raster images for 3D engraving projects.