Vectorize Using Illustrator (And When Not To For CAD/CNC)

Updated Jul 1, 2019
Adobe Illustrator icon on computer screen

Adobe Illustrator is a popular vector graphics editor used across the world to create digital graphics and illustrations like logos and icons. But did you know that you could use it to vectorize raster images? Using a feature called Live Trace, you can convert a raster to a vector which can then be used in websites and much more.  

This guide will show you exactly how you can vectorize using Illustrator. We’ll also highlight when you should use Illustrator, and when you should use software like Scan2CAD instead. Plus, find out how you can get a free download of Scan2CAD. 

Table of Contents

What is vectorization?

If you’re a novice in the world of CAD, CNC or graphic design, you might not know what vectorization is. It’s the process of converting a raster image into an editable vector image. This process is otherwise known as image tracing which can be done manually or automatically. 

Image of a manually traced letter Manual tracing was originally the only way you could create a vector from a raster image. You can trace over a raster using your mouse, or a tablet and graphics pen. It can be a more advantageous method to use, as you’re more likely to understand the image than a computer. As you can imagine however, this process can be rather time-consuming. 

Automatic tracing involves using a conversion software to convert your raster image to a vector. This process can be a lot quicker than manual tracing. However, you need to be working with high quality images for the software to be able to detect everything correctly. 

Not sure which method to use? Check out tracing: manual or automatic?

Why is vectorization needed in graphic design and CAD?

raster image example of letter 's'Raster images come with a variety of problems. They are made up of pixels which mean that when you zoom in, they lose definition and each pixel becomes visible. Rasters are therefore resolution dependent which can be an issue when you want to resize an image. The graphic design industry in particular relies upon artwork and designs that can be infinitely scaled—you don’t want to experience any loss in quality when enlarging. 

raster example image of letter 's'Vectors by comparison are mathematically perfect formats. They’re made up of paths which means that no matter how much you change the scaling, they won’t lose their quality. You can therefore use the same vector as a tiny logo on a business card or enlarged on a billboard—vectors are resolution independent.

In regards to CAD and CNC, vector drawings are much easier to edit because you can modify individual vector entities. They’re also much easier to store and share due to their small file size. If you convert to formats like DXF for example, you’re given greater accessibility as they can be opened in any CAD software. For more information, check out raster versus vector

Adobe Illustrator

Adobe Illustrator's logo Adobe Illustrator is an industry-standard vector graphics editor developed and released by Adobe Systems in 1987. It’s used by designers across the world to create digital graphics and illustrations like logos, icons, typography and illustrations for print, web and much more. It’s a companion product of Adobe Photoshop which you might also be familiar with. Photoshop is concerned with digital photo manipulation and photo-realistic computer illustration, whilst Illustrator is geared towards typesetting and graphic design. 

Illustrator can be used to create freehand drawings or to import photographs and images to trace over in order to create a vector. This is primarily useful for graphic design applications—the software can be lacking when it comes to CAD or CNC purposes, which we will discuss later. In addition, the software can be rather expensive, although it is aimed at professionals who are going to use it to its fullest capacity.

Vectorize using Illustrator

You could choose to manually trace your image in Illustrator, but we’re going to look primarily at automatic tracing. 

Adobe Illustrator comes with a handy image trace feature called Live Trace. It enables users to convert raster images to vectors and use feature presets to create various effects. This tracing engine can automatically apply the most appropriate tracing preset—offering users an intuitive and advanced interface. 

Start by placing your image into your Illustrator artboard. Once you’ve selected the image, click Image Trace. To see your options, click on the Image Trace Panel next to View. This panel contains a variety of preset tools that you can use to create certain effects within your image. 

Illustrator tools

  • Preset: you can choose the type of image you want to trace so that the software can set the variables needed to produce the vector, e.g. high fidelity photo, sketched art and silhouette. 
  • Mode: this defines the color of your image—color, grayscale or black and white. If you select black and white, you’ll be able to use the Threshold tool to adjust the black to white transition. 
  • Adobe Illustrator's color palette Palette: determines how the colors are chosen for your image trace. 
    • Automatic: switches between a limited and full tone palette. It analyzes your raster image and uses a suitable palette. If the image trace detects fewer colors in your image, it will use a limited palette tracing as a result. 
    • Limited: uses a small set of colors for the tracing palette. If your image has too many colors, it will either choose colors that are similar and close together or choose colors that take up the most area. 
    • Full Tone: determines the color palette by grouping nearby pixels of similar colors together to create each filled region in the result. 
  • Colors: the colors slider generates different results depending on the value selected for Mode and Palette. 
  • Paths: controls how closely the Bezier paths fit the pixel boundary—the lower it is, the fewer segments and control points it has. The curves of your image will then be much smoother. 
  • Corners: determines how likely it is that sharp bends will be turned into a corner point. 
  • Noise: specifies the size of the smallest areas of your raster image which will then be taken into account while tracing. 

All done…

You can check the Preview button at any point to see the results of your preset selection. If you’re happy with the result, click on Trace to convert your image into paths. Once you’ve done so, your image will be replaced by vector objects. You can use the pen tool if you need to make any tweaks or changes. Once you’re completely happy with your vector image, you can save it as any vector format including: 

  • AI: native format of Adobe Illustrator. 
  • EPS: an older print format. 
  • PDF: widely used for sharing and printing documents. 
  • SVG: used mostly for web graphics and interactive features. 
  • DXF: a data exchange format used in CAD. 
  • DWG: AutoCAD’s native file format. 
Live Trace in Adobe Illustrator

Before and after tracing an image using Image Trace

So now you know how to vectorize using Illustrator. But does this mean that you can use it for vectorizing any image you have? The answer, quite simply, is no. Adobe Illustrator is primarily used for graphic design purposes—if you’re looking for a more specialized approach for use in CAD or CNC, you’ll have to look elsewhere. Read the next section to find out when you should and shouldn’t vectorize using Illustrator. 

When Illustrator should and shouldn’t be used

Adobe Illustrator is catered towards graphic design. If you’re looking to vectorize your logo or use an image for your website, Illustrator will undoubtedly give you a great output. It enables you to produce vectors with a high number of colors and a high level of realism. It can even be used for simple designs in CAD or CNC—you could quite easily convert a logo in Illustrator, edit it in CAD software and send it to CAM for use with a CNC machine. 

If you’re trying to convert a technical drawing for CAD, you could use Illustrator—it does come with a technical drawing preset. However, it’s a generalized trace—the variables used will be the same regardless of whether you’re converting an architectural drawing or a mechanical drawing. In addition, Illustrator will take longer to convert a scanned image. If your drawing includes text, the live trace might not even detect it properly. This could lead to you having to re-write the text. 

The process of vectorization can also be time-consuming in Illustrator. If you’re vectorizing different types of technical drawings, you want to make sure that the variables used are suitable. Your architectural drawings for example, should retain sharp corners, whilst your contour maps should be converted into Bezier curves or splines. If you’re not happy with the results of the conversion, then you have to go back and make further modifications. So why not use a specialized solution?

What is Scan2CAD and how is it different?

scan2cad product box Scan2CAD is a two-in-one solution. It’s a raster-to-vector converter and a PDF-to-vector converter. Its primary focus is on the conversion of technical drawings like site plans to usable and editable vector images. It can be used by anyone in any industry—from mechanical engineering to infrastructure to product design. 

Adobe Illustrator has two main disadvantages when it comes to conversion for CAD or CNC: it only offers a generalized trace for all technical drawings and it can be a time-consuming process. Scan2CAD offers solutions to both of these issues. Scan2CAD comes with vector recognition for architectural drawings, contour maps and much more. In addition, it has specific vectorization settings that take different variables into consideration depending on the type of drawing you’re converting. 

In regards to time efficiency, Scan2CAD’s batch processing feature enables users to automate tasks on thousands of files at once. These converted files can then be opened in any CAD, CNC or GIS package. And with Smart OCR, you won’t come across any issues when converting raster text to vector text—you can even train the software to recognize new or handwritten fonts. 

OCR text extents

OCR in Scan2CAD

How does the process work?

Scan2CAD detects the lines and edges present in your image and redraws them as vector entities such as: lines, polygons, circles and Bezier curves. It takes into consideration a number of parameters including the angle of the curves, line weights and the type of line. Scan2CAD comes with pre-programmed variables and vectorization settings that control exactly how your conversion is carried out. It also allows you to make use of a raster and vector editing suite so that you can tidy up your image before and after conversion. 

Want to know what the best part is about using Scan2CAD? The process takes only a matter of seconds—as you can see below. 

Problems with conversion

Poor image quality

The quality of your vector output is dependent on your input file. After all, if you’re looking to convert a technical drawing for use in CAD, you need the ultimate precision. An architectural floor plan for example, is useless if it’s full of broken lines or shadows. You can tell your image is of poor quality if it contains any of the following issues: 

  • Heavy pixelation. Pixels become obvious, and the image looks blurry. 
  • Low resolution. Lines should be around 5 pixels thick to obtain a good vector output. 
  • Dithered lines. This usually arises with scanned pencil drawings. 
  • Merged lines. If your drawing has text written over a line, the software won’t be able to distinguish one from the other. 
  • Hairy lines. Essentially lines that have fuzzy edges. 
  • Shadows. Another issue that plagues scanned drawings. 
Poor image quality for raster to vector conversion

Don’t bother converting any raster image that sports any of these problems…

Converting before tidying up

If you try to convert your drawing before addressing any of these issues, your output vector won’t be of a high standard. Drawings need to be checked before and after conversion to ensure that all elements have been correctly recognized. The last thing you want is for one of your dashed lines for example, to be mistaken as short lines. 

Not choosing the right settings

Each image requires different settings when it comes to vectorization. As we mentioned earlier, if you’re working with technical drawings, you don’t want a generalized conversion. Scan2CAD comes with vectorization settings that allow for a more specialized conversion. If your drawing contains straight, orthogonal lines then it might be best suited to the Mechanical setting. If you’re looking to trace the outline of a solid shape, Outline might be more to your suiting. It even comes with a setting for CNC designs

How to get the best results

Scan2CAD supports a variety of file types, allowing you to convert from a number of raster files to a vector file format of your own choosing. In order to produce the optimal result possible however, you need to tidy up your image. Scan2CAD has a series of tools on offer that can be used so that you don’t have to make further changes in the CAD software you take your drawing to. 

Pre- and post-processing work

  • Pick the right format. If you’re working with scanned images, you should save them in the TIFF format which comes with lossless compression. You need to start with the right format to ensure you get the best result. 
  • Reduce colors. Ideally, you want your raster image to have as few colors as possible in order to give you the clearest possible contrast between the background and foreground. Reducing colors is vital, because the converter will detect every shade and produce separate vector entities as a result. 
  • Thresholding. This allows you to divide your raster image cleanly into black and white pixels. It’s especially important with scanned images that often come with grayscale or compression artifacts. There are two types of thresholding: 
    • Simple thresholding: applied to the whole image. 
    • Adaptive thresholding: applied to different parts of your raster file. 
  • Deskew the image. If your drawing is scanned at a slight angle, it won’t be converted into clean, straight lines in the vector. Scan2CAD’s deskewing tools will fix this problem. 
  • Cleaning tools. Scan2CAD comes with cleaning tools that you can use to combat the problems highlighted earlier. 
    • Remove holes or speckles
    • Thicken lines to fix broke or dithered lines. 
    • Smooth to remove hairy edges surrounding your image. 


Of course that’s just the tip of the iceberg. You can check Scan2CAD’s raster quality checklist to see how you can fix any further issues you might come across. Alternatively, take a look at our top 10 raster effects for more ways to optimize your raster before the conversion process. 

All sorted?

Once you’re happy with your image, you can move on to the easiest part of the entire process. Unlike other conversion software, Scan2CAD can convert your drawing in a matter of seconds. Once the vectorization process is complete, you can then save your new vector as a DXF, DWG or even as  G-code ready for use with CNC control software. With Scan2CAD, it couldn’t be easier—as you can see below. 

Floorplan before and after DXF Conversion - Raster to Vector - Scan2CAD

Here’s a floorplan — before and after conversion! We’ve used Scan2CAD to convert it from a scanned image (left) to an editable vector (right); and saved it as DXF

Scan2CAD: free download

If you’re converting images for graphic design purposes, then go ahead and continue using Adobe Illustrator. If you’re looking to convert technical drawings or complex designs for use in CAD and CNC however, why not give Scan2CAD a try?

Whether you’re a hobbyist or a professional, Scan2CAD offers you a specialized solution for all of your vectorization needs. Scan2CAD has been used across industries for a range of uses from routed signs to metal sculpting to glass reproduction. Plus it can be used for CNC projects like laptop decals, wooden plaques and stencils. It’s the ultimate vectorization software

So instead of messing around using software like Adobe Illustrator or outsourcing your CAD designs, why not convert them yourself with Scan2CAD? You can try out the software in a free 14-day trial with absolutely no limitations—you can convert as many files as you want without watermarks. Just click on the button below to get started. 

Download Scan2CAD Free Trial

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