Drawings from books, blueprints or other technical drawings and even logos from business cards can be used successfully as line art from a scanned file.
Image Credit: istockphoto.com, Antique illustration of a corncrake (isolated on white). Published in Systematischer Bilder-Atlas zum Conversations-Lexikon, Ikonographische Encyklopaedie der Wissenschaften und Kuenste (Brockhaus, Leipzig) in 1844.

As a professional working with graphics, you know that high-quality source files lead to high-quality-looking customized products. Many times, though, receiving quality files from clients an be next to impossible. This is the second in a series on scanning tips. The focus of this piece is on scanning line art. Typically, you might encounter line art when a customer hands you a business card with a request for sublimation promotional products such as an EZ Sign, key chains, mugs, or magnets. These tips can also help when working a drawing or a technical blueprint.

Line art (defined on wikipedia.com®) “… is any image that consists of distinct straight and curved lines placed against a (usually plain) background, without gradations in shade or hue to represent two-dimensional or three-dimensional objects. Line art can use lines of different colors, although line art is usually monochromatic.” In addition to a flatbed scanner, you’ll need an image manipulation program like Corel® Paint, Adobe Photoshop®, or Adobe Photoshop Elements®.

Get In The Modes
Improving the quality of a line art file can be accomplished with a few techniques applied during and after scanning. There are mainly two different modes for scanning when working with line art: grayscale and line art or black and white mode. I have a simple flatbed desktop scanner (a Cannon 8400F) that’s a few years old. It is not complicated but does a very nice job for everything I’ve needed in the last three years of using it—and it still works. Within the scanning software is where I find the Color Modes menu.

Grayscale (or even scanning in the Color mode to have a reference for their colors) is the safest mode—especially if you will be working on multiple levels of pieces for a customer in the future. Grayscale mode should be scanned to the size of how it will be used at a resolution level of 600dpi. If you don’t know what the final size will be, try scanning it at 150%; this gives you a little extra ‘fudge’ room.

The scanner will move slower than usual to obtain information. Make sure the print is placed into the scanner as straight as possible. This will help the quality of your scan. Grayscale can be more forgiving for tweaking and is best when working with a file that is not primarily black and white. If you scan in grayscale, you can convert to bitmap mode for your final printing if that is what will work best for the project.

Line art or Bitmap mode is the most common and will likely be the most successful a majority of the time for ‘flat’ line art. This form of line art is typically one or two colors that are higher contrast or just black and white. The art will be used again with two colors or one color, including solid white, black or another color. Scanning at the line-art level allows for only simple editing. The black and white (bitmap) mode in the particular scanner mentioned above does not allow for adjusting the threshold while scanning so the best manner is to scan in grayscale mode, then further edit in Adobe Photoshop from there.

Cleaning Up
While viewing the image at 100%, the jagged edges and holes become more clearly visible. To clean up jaggies (jagged edges), use the pencil tool. With black and white in the color blocks, the pencil tool will erase and add information to your file easily. Be sure to take a look at the piece as a whole frequently while working to make sure you don’t remove too much where you don’t want to clean up.

Use the pencil tool to fill in areas that seem to need some additional pixel information. Bitmap mode allows you to easily select the scanned art using the magic wand tool (for example) in Photoshop. When you are working with straight edges, hold down the shift key and move the cursor; you’ll be sure to get a nice, smooth line.

Contrast And Clarity
Challenges can be encountered to obtain a clean, usable scan when using a third-generation print (copy of a copy), artwork provided on colored paper, or with low contrast (on a technical blueprint, for example). One way to compensate for the low contrast is by adjusting the threshold when scanning your file.

Line-art mode scans the file and determines whether a dot should be pushed towards black or white. If the image is light (or thin lines are disappearing), then increase the threshold value. If the scan is picking up too much information (more lines than should appear in the art, or areas are becoming plugged with black when the space should not), then lower the threshold.

The goal is to change the threshold settings to distinguish the tonal ranges between the background and foreground. It may take a test scan or two to find the right threshold range. By using the preview function in your scanning software, you can limit the time this takes.

Another helpful tip: make a note of what threshold value works best for that file. Once you’ve worked with a few line-art or drawing files, finding the threshold will become easier. If you are scanning in grayscale mode, you can convert the file into a bitmap and clean it from there easily, using the pencil and eraser tools.

A Note On ‘Show Through’
In the previous article in this series, I discussed ways to scan an item that might be showing the opposite side of a page—for instance, with a newspaper or magazine article. When a client gives a pre-printed file to use as a source, always be aware of what the intentions are with the file and if they have or need permission. The last thing you want to add to your to-do list is addressing a copyright infringement claim.

The best way to resolve this problem is by using a piece of black (construction paper works fine) paper. If you don’t have a sheet of black paper accessible, print a page that has black ink covering the entire sheet. The goal is to block the light of the scanner from going entirely through the page. I’ve been using this trick for 14 years, and it still works great on scanning projects.

Working With Artwork
Sometimes, working with provided artwork is a challenge, especially when the art provided is smaller than what is requested for the final output. Scanning the file at a high resolution (of 600dpi) and then resampling the image, or scanning the file as close to final print size as possible are the two best ways to go about enlarging a file. You can find the resampling functions in the image-size windows typically.

For Photoshop specifically, you can find it under the top menu bar item of Image > Image Size. One of the boxes at the bottom of the pop-up window is labeled Resample Image. When it is unchecked, the image dimensions and resolution will all be linked together. By adjusting your size in this manner, you can avoid enlargement problems.

Ending Note
There is ‘fudge’ room with all of these techniques. With line art, you can usually massage the file to work well enough, no matter what you have received.

Educating your clients is the best way to resolve this matter. Create an Adobe Acrobat PDF file of suggestions, file types and other material-requirement notes that you can easily email or post on your website (limit to one page). Keep printed copies (black and white is fine) in your shop to hand out to customers and to use as a reference.

Thank you to Dan Rutledge of Unique Imaging Concepts (www.uniqueimaging.com) in Louisville, Kentucky, for allowing the use of the company logo in some of the visual samples presented in this article.


Jennifer Foy has over 12-year’s experience using Adobe Photoshop. She has received a Bachelor of Fine Arts in Visual Communications from the Ringling School of Art and Design in Sarasota, Florida. Her years of teaching experience include numerous software and design classes in Adobe Illustrator, Photoshop, QuarkXPress, Freehand and InDesign for Colleges in Atlanta, Georgia; and Louisville, Kentucky. While currently finishing an Independent Study Masters Degree program from Syracuse University in Advertising & Design, Jennifer is working as the creative director for Unisub Color Product Solutions. Jennifer can be reached by email at jenniferf@unisub.com.