Raster to Vector Guides

Buyers’ Guide: Choosing the Best Scanner for Converting Paper Drawings to Vector

A successful conversion relies on the quality of the image, which is, in turn, reliant on the TWAIN or WIA scanner you’re using. This, therefore, ranks the scanner and poor-quality scanned images as the biggest hindrances to good automatic vectorization.

Several factors result in a reduction of the quality of the scanned images, chief among them being the lack of knowledge and expertise. Scanner manufacturers usually market their products as being easy to use. As a result, the scanning work is more often than not assigned to inexperienced workers, even when the scanned images are of extreme importance. As such, in a large firm, you might find that unskilled workers archived images or documents, and this resulted in unusable documents, particularly when vectorization was or is needed.

This analogy shows that the manufacturers’ marketing strategy is usually very far from the truth. A scanner’s operations are governed by a plethora of settings, some of which require the operator to have a technical understanding of their capabilities. For instance, in some scenarios, grayscale is preferred to monochrome or black and white settings. Why? Because with grayscale, the scanner captures more information than it would have had the operator chosen black and white.

Canon iPF8400SE MFP wide format scanner
Canon iPF8400SE MFP wide format scanner (Source)

However, successful vectorization requires the raster image to be scanned in monochrome. It, therefore, follows that scanning is all about balancing and knowing what purpose the scanned image(s) will serve.

Granted, your firm may have archived important documents somewhat haphazardly, perhaps because this task was assigned to an inexperienced worker. And this may have been so long ago that you can’t rescan the original documents or images. All isn’t lost because, nowadays, vectorization software packages, such as Scan2CAD, enable the rectification of most of the issues you might come across while dealing with the scanned images. However, success doesn’t happen 100% of the time – there’s only so much that the vectorization software can do.

As such, to protect those who come after you from experiencing many of the frustrations you’ve experienced – if you happen to work in such a firm – it’s crucial to follow the recommendations highlighted herein. To this end, this article is designed for anyone looking for advice regarding the best scanner to buy that would be suitable for automatic raster to vector conversions.  

Scanner Applications

Scanners are applied in duplicating either graphics (photographs, artwork, etc.) or technical imaging or drawings. The term technical drawing generally refers to designs used for any survey, architectural, or engineering work – they could be GIS maps, mechanical drawings, architectural plans, electrical schematics, and images used for any of these listed purposes.

Scanning technical drawings require a monochrome setting, wherein there is only a limited number of colors. In most instances, only black and white are needed. On the other hand, graphics require color images. Besides the color requirements, scanners also come in different sizes to accommodate the various sizes used in graphical or technical drawing work.

Paper Sizes

Artworks, technical drawings, and some photographs are often painted or printed on large documents, i.e., A3/B-size, A2/C-size, and A1/D-size papers. This, therefore, calls for a large format scanner since it’s only this type that can accommodate the larger paper sizes. For this article, the assumption is that you intend to use the scanner for CAD/CAM applications.

CAD/CAM Applications

Now, in CAD/CAM applications, scanners are used to convert technical drawings – printed or drawn on paper – into vector images so as to open them on CAD/CAM software.

The smallest commonly used size for technical drawings is A4. This is particularly so for small projects. However, for larger projects whereby the technical drawings contain much more details, larger paper sizes are often used. In this regard, if you’re in the market looking to buy a scanner for your engineering or architectural firm, then large format scanners are the most ideal for you.

Large Format Scanners

The terms ‘wide format’ and ‘large format’ are used interchangeably. So, you shouldn’t get confused. In fact, typing ‘wide format scanners’ on Google’s search bar and hitting ‘enter’ yields results that mainly talk about large format scanners. This is primarily because large format scanners are described as peripheral devices that duplicate wide paper sizes.

Large-format scanners are less flexible than other types because, while you can use the latter to scan just about any document, the former variant primarily handles a specific type of document. But the good thing about their specialization is that some large format scanners are made with efficiency as the objective.

How so? You’re likely to find that some technical drawings were archived by printing them on the blueline, sepia, or Mylar sheets. It shouldn’t also come as a shocker that, because the sheets are large, they were folded to occupy less space. Efficient scanners can scan folded documents that were printed on any type of sheet. With this in mind, I must point out that not every large format scanner can handle these many constraints. As such, always keep in mind that the scanner you buy should deal with such issues with the utmost ease.

A scanner’s ability to handle the constraints depends on the scanning technology they deploy while scanning. A scanner has either CIS or CCD technology, thereby implying there are two types of large format scanners.

Charged-Coupled Device (CCD) Type Scanners

Charged-Coupled Device (CCD) scanners contain separate modules. Each module houses its own component, i.e., lenses, the source of light, and imaging parts/camera. These three components determine a scanner’s image quality and flexibility.

Given that, in CCD scanners, lenses, light sources, and sensors are separate, the scanned image or document is usually of very high quality because these devices capture more colors accurately. The only downside is that CCD scanners require a lot of maintenance.

CCD Scanner Components
CCD Scanner Components Source

Contact Imaging Sensor (CIS) Type Scanners

Contact Imaging Sensor (CIS) scanners combine the lenses, lighting (color LEDs), and imaging components (sensors), as in the image below. As such, compared to CCD scanners, CIS scanners are much more integrated. CIS scanners utilize a fiber optic lens array to focus light from the document or image to the sensor.

Combined Lens, Sensors, and LED
Combined Lens, Sensors, and LED Source

However, CIS scanners are less efficient because they sometimes struggle to represent some colors, particularly when these colors are outside the range of what constitutes primary colors. This makes them unideal for graphics work where the artists or photographers need the scanner to capture a wide range of colors accurately.

The upside is that they don’t require a lot of maintenance, and they provide sharper scanned documents, particularly in technical drawings, because they duplicate fine line details perfectly. Thus, CIS scanners are the best type for CAD, GIS, and AEC (Architecture, engineering, and construction industry) applications.

Accuracy of Scanners

Remember, scanners have a plethora of settings that enable them to produce quality images. Dots per inch (dpi) happen to be among the most critical settings. Dpi is the scanner’s optical resolution that denotes the number of sensors across the width. As such, a 600-dpi scanner has 600 sensors per inch.

Most manufacturers of good large format scanners provide excellent resolution. Some even claim to sell scanners with a resolution of 9600 dpi or even higher. But as we mentioned above, the manufacturers’ marketing strategy is usually far from the truth – a lie if you wish. The resolution advertised is another parameter that supports the assertion. Such extremely high resolutions are generally a result of interpolation using the software. The highest ‘natural’ value is around 1200 dpi.

Dpi dictates the scan resolution, the file size of the scanned document, and the time your printer will take to finalize scanning. Besides these three parameters, the kind of image you’re scanning determines the dpi you’ll choose.

For instance, a document containing a small logo will require a high dpi setting. On the contrary, a document with just a few line drawings will require a lower dpi setting of, say, 200 dpi. As such, even if your scanner has a resolution of 1200 dpi, that doesn’t mean that all your scans should be undertaken at this resolution.

Technical drawings are made up of lines and curves which are printed in monochrome. They don’t feature a lot of information because they don’t utilize many colors or gradients. Still, some line artworks are colored. Such pieces are best scanned at 900 dpi because, at this resolution, the scanner captures even the finest of details. However, most line drawings are printed in monochrome, and the optimal scan resolution you should use for such is between 200 and 400 dpi.

Many other document types have their preferred dpi resolutions, but that’s beyond the scope of this article. The bottom line is that the higher the dpi resolution, the more information the scanner will capture. Hence, the higher the accuracy.

Scanner brands you should consider

After reading the sections above, you might still be asking yourself, ‘What scanner brands should I consider?’ Well, you’re in luck because that answer is in this specific section. A comparison of two reviews by Ezvid Wiki and Gearhungry reveals that you should consider the following brands (in no particular order):

  •  Xerox
  • Canon
  • Graphtec
  • Colortrac
  • Epson
  • Contex
  • Plustek

Your choice of the particular scanner to buy depends on your budget and personal preferences. The latter could be that you usually buy from the leading manufacturers. Well, Colortrac and Contex are the top manufacturers of large format scanners.

It’s advisable that you read about each of the manufacturers on the list and the various scanners they make. What I know for a fact is that any scanner from the manufacturers listed above won’t disappoint you. They develop quality equipment, guaranteed to last you a long time.

Cost of Scanners

The price of the scanners from the manufacturers whose scanners appear on Ezvid Wiki and Gearhungry reviews range between $250 (Xerox) and $7500 (Graphtec). Other scanners go for as much as $40,000.

The precise model you’ll buy will depend on factors such as the features, technology, and size. Also, given the availability of scanners at every price point, the general rule of thumb that should guide your purchase is to buy the best you can afford – always remain within budget.


Some manufacturers, e.g., Contex and Colortrac, manufacture both CIS and CCD scanners. On the other hand, some, such as Graphtec, only produce CIS scanners. If you’re looking for a scanner for color images, then a CCD scanner is the best option for you. If you’re in the AEC industry or looking for a scanner to enable you to duplicate, archive, or vectorize technical drawings, then CIS scanners are your best option.

Having said that, manufacturers misrepresent facts. For instance, they could claim that their scanners support high-speed scanning. But this may end up being a big lie leading to inconveniences on your part. As such, conduct due diligence by consulting multiple reviews – both video and written – before coming up with a verdict.