Raster vs Vectors and how they work on Fiber Engravers

Understanding the differences between raster and vector files when engraving on fiber.

Fiber laser engravers make use of 2 main file types, rasters and vectors. I see clients, mainly corporate like ODW and a couple others who make use of, almost exclusively, raster based graphics when they engrave. I'd like to share the key differences and shed some light on which files we should be using ideally for engraving.

Firstly we need to understand the differences between raster and vector files;

  • Raster files are images built from pixels — tiny color squares that, in great quantity, can form highly detailed images such as photographs. The more pixels an image has, the higher quality it will be, and vice versa. The number of pixels in an image depends on the file type. Common raster types include jpg, png, jpeg, bmp, tiff and more. Raster images are the everyday images you find online while browsing the internet or on social media sites.
  • A vector, in mathematics, is defined as : " a quantity having direction as well as magnitude, especially as determining the position of one point in space relative to another ". Vector files are images that are built by mathematical formulas that establish points on a grid, they essentially are built with lines as opposed to pixels. Common vector formats include : svg, ai, plt and eps files.  

Secondly we must understand their place in design;

  • Vectors are better to scale. The concept behind vectors is a mathematical equation that makes them perfect for extending and reducing images. Raster images are made of blocks (pixels). Stretching the blocks will make them less sharp, resulting in a visible image quality degradation. Even shrinking can cause data loss at times.
  • Vector files typically require less space. The vector size is calculated according to the image size, thus they are more optimized than raster images. Typically, they are much lighter than raster files. Of course, it doesn’t mean vectors are always light. Adding multiple effects can create many dots and lines that will eventually lift the file size by a lot.
  • Vectors are used mainly as working files. If you are a designer, it will be way easier to save files as vectors, rather than bitmap images, as you can edit them on the go, save space, and open them faster, once you need them again. Rasters are much less flexible, making them a better option for final files.
  • Rasters work better for colours. Being the larger files has some advantages. Each pixel captures data that is unique. This could create more shadows and an extra depth of the image. However, stretching the images might create a blur that will quickly turn this into a disadvantage, so you have to be cautious.

So now that you know a little bit about these file types, how do we apply them to Fiber engraving and EzCad?

The only time one will seak to use a raster based file in EzCad is when dealing with pictures such as; a selfie, or a photo of a pet, or a wallpaper of a car. The way Ezcad interprets a raster or bitmap file is it will convert the file into 2 parts, a greyscale powermap and a dot map. The greyscale powermap works from a scale of 0-255, 0 is pure white and 255 is pure black, as you can see there's over 5x more than 50 shades of grey. Each number on the greyscale is assigned a % value on the powermap (of which the user is able to edit and define each number a different power % to), for example 50% laser power is assigned to the 127/128th number on the greyscale, 255 would be 100% laser power. Please be aware that if you set the hatch layer in EzCad to 50% for example then the "100%" in the powermap will actually be around 50%. The second part of the raster is a dot map, each pixel becomes a dot, this reflects the physical spot of the laser beam, so the laser can be imagined as a pen poking dots horizontally across a page. It's easy to imagine that after all of this extra work the software goes through; our engraving will be super slow and tedious because now the laser is focussing on marking each individual pixel row by row and it needs to pay attention to the amount of power each dot receives.

So with the above it is very important to consider what you will be engraving, if it's a picture file format then go ahead, it's simple to get one into EzCad, just download the picture and import it via the Bitmap import feature but be aware, if the file type isn't supported you wont be able to use it. Also because rasters can come in many sizes, you can struggle with low quality (pixel count) images as you will not have enough detail to produce a good outcome. Material choice also matters as metals have different reactions to the laser beam, typically a raster works best on a painted metallic surface or certain types of stainless steels.

If the picture is a logo, such as a black and white image, then you should ideally opt for vector. Vectors can technically resolve an infinte resolution, the limit is the physical capability and accuracy of the laser following the co-ordinates of the vector file. Anything that is a basic or complex shape/outline should be a vector, any text in EzCad is a vector. Vectors are not meant to resolve "life like" images or portraits; they suit a more practical role like names, serial numbers, shapes and logo designs but you typically can't simply download vectors off of the internet like images. You will likely have to pay money or sign up to websites (or contend with stupid water marks) where artists make their own vectors and publish them on such sites. Alternatively you should have editing software like coreldraw or adobe illsutrator at your disposal. Raster images can be converted into vectors through the use of clever techniques involving tracing and editing. If you see a picture you like but want it in vector format, you will have to go the extra mile and convert it or just entirely make ones from scratch.

Here is a useful table of all mainstream software and their ability to import vector formats.

Platform AI
open/edit
SVG
open/edit
PDF
open/edit
EPS
open/edit
CDR
open/edit
Adobe Illustrator Yes/Yes Yes/Yes Yes/Yes Yes/Yes Yes/Yes
CorelDRAW Yes/Yes Yes/Yes Yes/Yes Yes/Yes Yes/Yes
Affinity Designer Yes*/No Yes/Yes Yes/Yes Yes/Yes No/No
Canva No/No Yes/Yes Yes/Yes Yes/No No/No
Inkscape Yes/No Yes/Yes Yes/Yes Yes/Yes Yes/Yes*
Gravit Designer Yes/Yes* Yes/Yes Yes/Yes Yes/No No/No
Vectornator Yes/Yes Yes/Yes Yes/Yes No/No No/No
Sketch Yes/No Yes/Yes Yes/No Yes/No No/No
Figma No/No Yes/Yes Yes*/No Yes*/No No/No
Adobe Photoshop Yes/No No/No Yes/No Yes/No No/No
Vectr Yes/No Yes/Yes No/No Yes/No No/No

 * – it is achieved via file conversion

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