Auto-Tracing: How To Convert Bitmaps To Vector Drawings

Digital Imaging

In the early days of desktop publishing (1985-1990) I was fascinated by the opportunity initially made available by Adobe Illustrator and by some AutoCad utilities to convert bitmap work and in particular technical photographs into quality line drawings.


Vectorization, known by many in the publishing, GIS and graphic design industries, allows a bitmap image, generally derived from a scan or from other digital input acquisition equipment to be converted into a much more manageable, flexible, light and editable vector format.

Bitmpap images are made of a series of dots or pixels.

Vector images are instead described by mathematical formulas.

Bitmpap images are consequently:
a) large in size
b) very hard to edit
c) difficult and slow to manage

Conversely, vector images are characterized by:
a) very small size
b) completely editable
c) resizable without loss of quality
d) easy and fast to manage

Therefore, as you can clearly see, there are several advantages, in certain application areas, like technical documentation, to have high quality vector illustrations and maps for all needed references. This in turn guarantees great savings and the ability to easily edit, update and change large amounts of visual references that are part of critical technical documents.

At the time, 1989, I had to create technical illustrations for airplanes operating manuals showing in a professionally drawn outline parts and sections of the aircraft were maintenance or parts may have needed changes or maintenance. The technique adopted was to shoot on the actual aircraft best quality black and white photographs of the different parts. During the shoot we made sure we had always strong sharp contrast in our images and we used selected film for this purpose as well. Once the photographs were developed and printed (we had no digital cameras at that time) we scanned the images into a computer, and then worked to manipulate contrast and brightness of the image in a way that would leave us with the "essence" of what was actually there.

At this point we would start auto-tracing, initially with Adobe Illustrator limited functionality and then later on with more automatic and sophisticated tools like Adobe Streamline.

Once that was done a capable technical illustrator would then take the newly created Illustrator vector files and she would clean-up and refine them until perfection.

As I grew more familiar with the technique and the tools available I realized how much potential was out there for businesses living on paper-based visual references that had no digital counterpart, requiring therefore large costs for updating and changing the information therein contained.

I later experimented with good success the conversion of airplane landing maps, which again, at the time (1989) were still largely paper-based and uneditable on any digital computerized system.

Bitmap to vector conversion is a difficult, highly technical and time consuming task. There is no program or utility which can vectorize the image you have at hand into perfection simply because the software doesn't know which is the end result that you need to arrive at.

This is why bitmap to vector conversion work requires dedicated time, patience and several trial and error sessions in which to fine tune the best procedure and workflow to adopt for your specific assignment.

Here is my best effort at creating an updated and comprehensive resource list that you can utilize to support and facilitate your conversion of bitmap artwork into quality vector drawings:

Illustrator Tracing tutorial
This is a tutorial where you'll learn how to do those nice looking traced images like the one to your right. Now, I know there is a lot of software out there that will do this work for you, such as Adobe Streamline or Flash with its bitmap tracing option,
but I'm sure you'll agree with me that there's nothing like the real thing baby, so let's get on with it and get some skills.

Illustrator How-To: Turn Bitmap Images into Vector Art
Transforming the jagged edges of raster images into the smooth curves of vector art isn't hard to do using Adobe Illustrator's Auto Trace feature. But the end result can look simplistic. For more sophisticated images, you'll need additional help from Illustrator's path-editing tools and from your image editing application. Here's what you need to do.

Adobe Streamline
Faster than a tracing hand, able to leap from raster to line art in a single bound, Adobe® Streamline™ 4.0 software instantly converts scanned black-and-white or color raster images into editable Adobe PostScript® line art. Just scan any sketch, and Streamline will automatically create a file that you can drag and drop into Adobe Illustrator® to complete your design.
User to user forum

TraceIt Bitmap Tracer
TraceIT is a program for raster to vector conversion. Based on original algorithms TraceIT provides the maximum speed for bitmap tracing. TraceIT can operate with a wide range of raster formats including almost every bitmap type such as: BMP, GIF, TIF, JPG, PSD etc. In addition to standard bitmap images, TraceIT can also trace video files in AVI, MOV or MPEG formats. TraceIT can extract some exact frames from video file, trace a range of frames or a whole file.

Rastervect - raster to vector conversion
The purpose of RasterVect is to quickly convert uneditable scanned paper drawings into accurate vector files for editing (as a CAD drawing) in any CAD program. It saves the converted file as one of vector formats: DXF, WMF, EMF, EPS or AI that can be read by any CAD program that supports these formats, including AutoCAD R14, 2000, LT and similar, like Corel Draw, Adobe Illustrator, Microstation, VectorWorks, TrueCAD, FastCAD and many others.

Vector Eye - The easiest way to convert images to line art
Faster than a tracing hand, this powerful software is the raster to vector converter you need for Illustrator (Adobe), CorelDraw (Corel), Flash (Macromedia), WebDraw (Jasc), Sodipodi (freeware) and any vector-based software. Vector Eye instantly converts scanned black-and-white or color raster images (bmp, jpg, tiff, png) into editable vector files (.svg, .ps, .eps). Just scan any sketch, or select an image (or a sequence) in an AVI movie, make some bitmap adjustments (scale, select zone, enhance, swap colors, rotate...) and Vector Eye will automatically create multiple SVG file corresponding to different settings. You can analyse, modify till the result suits you (quality, weight, number of vectors).

Freehand autotrace for beginners
The FreeHand Autotrace tool converts bitmap objects into vector paths. In addition, FreeHand can also autotrace other vector objects which may already be on the page. Before FreeHand 7, the Autotrace tool was useful for converting only the most basic scans into vector bezier curve art. However, in FreeHand 7 the Autotrace tool was completely rewritten. It is now a very powerful tool, capable of producing traces equal to (and sometimes better than) Adobe Streamline.

Silhouette provides quick tracing and a number of tools for tweaking your vectorized image, but don't start requesting only bitmap files from your clients just yet. FreeSoft has made its name in the sign-making industry with its FreeSign program for creating the quick signs you see at so many "signs-in-a-hurry" places. The machines that create those signs require vector images to complete the cuts, so it's easy to see how that could lead to a demand for a product like Silhouette. Silhouette is a plug in for Adobe Illustrator 8, 9 and 10 to convert bitmap images to vectors images with unique correction tools. It instantly converts black and white or colour bitmap images into vector designs ready for use.

Vextractor is a tool for transforming raster images into vector formats by building centerlines and outlines. This vectorizer tool could be used for vectorizing of charts, maps, schemes and other similar images for input to CAD & GIS systems. An application has an option to setup a reference for images, in other words to assign a real coordinates to certain raster points. Thus, you can get vector data not only in the raster coordinates, but real geographical coordinates or in the chart coordinates.

Traceline changes scanned or imported bitmap images to editable outlines (line art) that can be exported or pasted to other programs. This powerful app allows you to convert company logos, hand-drawn graphics, cartoons, and photos to editable, scalable outlines. An impressive number of raster formats can be imported. Use Traceline's intuitive editing tools to "tweak" your outlines for ideal results. Quickly switch between the Object Editor, the Node Editor, and Freehand Drawing. The program's vectorized output can be used in sign making, engraving, routing, animations, graphic design, and desktop publishing -- or in any program that accepts .wmf, .emf, or Adobe Illustrator files.

AutoTrace - converts bitmap to vector graphics
The aim of the AutoTrace project is the development of a freely available application with a functionality similar to CorelTrace or Adobe Streamline. AutoTrace is free software. AutoTrace is distributed under the term of GNU GPL.
AutoTrace currently comes in source code and some binaries - you have to compile the package for other platforms yourself. After downloading the archive, unpack the distribution and use make to compile it. Here is a short description of currently supported formats: Input formats: BMP, TGA, PNM, PPM, PGM, PBM and those supported by ImageMagick. Export formats: Postscript, svg, xfig, swf, pstoedit, emf, dxf, cgm, mif, p2e and sk

Converts your scanned documents (bitmap, raster, etc) to vector documents suitable for use with AutoCAD, Adobe Illustrator, and many other applications. Crucible converts raster (bitmap, scanned) drawings and other documents into vector-and-text (object) documents that can be directly used by such systems. Crucible converts documents that have any arbitrary combination of text and graphics, effectively discerning between the two forms of information. Crucible can convert black and white, gray-scale, and full-color documents. Crucible is very fast on standard desktop and laptop computers and can handle virtually any type and size of scanned document. Crucible's ability to recognize text in the midst of complex graphics is unsurpassed.

Professional raster to vector conversion software capable of cartographic data management tasks.

Traceline - Convert images to vector outlines
TraceLine converts scanned and imported bitmap graphics to scalable outlines that can be used in other applications for any use. TraceLine can be used by anyone that wants to: Convert hand drawn sketches to editable paths, Convert logos and graphics to editable paths, Convert photos to editable paths.

How do the Trace Bitmap Settings in Macromedia Flash Work?
The settings in the Trace Bitmap dialog box are touched on briefly in the Macromedia Flash manual, but this TechNote will provide a more thorough explanation of these features.

ImpressionX supports many popular formats including bmp, jpeg, tiff, pcx, etc.. It converts bitmaps to vector files and can create stencils and masks for airbrush friskets, printing techniques or other techniques.

Turning bitmaps into vector graphics with Flash
Old article showcasing how Flash 3 has a function called Trace Bitmap that works better than anything else at turning PICTs, TIFFs, JPEGs, BMPs, and even WMFs into vector graphics.

Acme TraceArt
TraceART is a professional raster to vector conversion program. TraceART can let you quickly convert uneditable scanned paper drawings into accurate vector files for editing in any CAD program. It saves the converted file as an industry standard DXF file (Data Exchange Format) that can be read by any CAD program that supports this format. TraceART is a direct replacement for traditional tracing and digitizing.

Tracing manually

Xara Bitmap Tracer

Coreldraw bitmap to vector facility

Convert bitmap to vector - Asylum FAQ

Autotracing tips
If you decide to autotrace, even if you know the angels will weep for you, remember these four tips.

I hope this proves to be a useful and lasting reference for anyone needing to do effective bitmap to vector tracing.