Adobe Illustrator 2022, the foremost vector graphic creation and editing tool in the commercial space, has a tracing feature that can turn raster works into vector ones, for high-precision editing. The tracing tool offers a variety of ways to trace, with retention of various details (but not full transfer of lines, textures, and colors of the original). Even with the various limitations, there are practical uses to be able to trace in an automated way. A short section will introduce human manual tracing practice on Illustrator, using the pen, pencil, and other tools, as a comparison.

1. AUTOMATED TRACING(S)
OF DIGITAL VISUALS
IN ADOBE ILLUSTRATOR 2022
Shalin Hai-Jew
SIDLIT 2022
July 27 – 29, 2022

2. PRESENTATION OVERVIEW
• Adobe Illustrator 2022, the foremost vector graphic creation and editing tool
in the commercial space, has a tracing feature that can turn raster works
into vector ones, for high-precision editing. The tracing tool offers a variety
of ways to trace, with retention of various details (but not full transfer of lines,
textures, and colors of the original). Even with the various limitations, there
are practical uses to be able to trace in an automated way. A short section
will introduce human manual tracing practice on Illustrator, using the pen,
pencil, and other tools, as a comparison.
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3. MANUAL TRACE
(as a comparative)
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4. MANUAL TRACE
• In general, a manual (by hand) trace begins with the selection of a
reference work (or multiple reference works).
• The reference works may be born-digital (photos, diagrams, digital drawings) or
born-analog (physical works on various papers or mediums that are digitized or
digitally photographed).
• Generally, the reference layer is placed at the bottom of the layers, and this
layer is locked in place. The translucency / opacity of the layer is adjusted,
so that it does not dominate higher layers above but just provides enough of
a hint to create the draft.
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5. MANUAL TRACE (CONT.)
• Common tools for manual trace in digital image editing tools include various
tools in combination:
• In Adobe Illustrator, there are the pen tool, curvature tool, line segment tool,
paintbrush tool, and others.
• In Adobe Photoshop, there are the brush tool, pencil tool, eraser tool, pen tool,
freeform pen tool, curvature pen tool, line tool; there are less obvious tools, like
the shape tool, and others.
• One can draw with absence and erasure (not only presence). One can draw
with control of white spaces. One can draw with suggestion. One can draw
with words.
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6. COMPUTATIONAL TRACE
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7. COMPUTATIONAL TRACE
• A computational trace transcodes a “seeding” visual or image into trace
data.
• Trace data may be expanded and ungrouped, so that all the computer-
drawn paths may be edited further.
• Computational tracing is apparently always reductive and summary. It does
not work in additive ways. It generally simplifies; it does not generally
complexify.
• In Illustrator, it works with mainline digital image file types, not proprietary
RAW images from digital cameras.
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8. COMPUTATIONAL TRACE (CONT.)
• There are a variety of computational trace sequences enabled in Adobe
Illustrator. The descriptive windows during the process may give a sense of
what is going on computationally in the software.
• One of my favorites goes as follows: smart blur, initial pixel clustering, path
smoothing, boundary refinement, path smoothing, and curve fitting. [I had to
run this on a particularly complex seeding work before I could catch the various
phases.]
• The different traces seem to have different processing sequences.
• A general one seems to include initial pixel clustering, boundary refinement, path
smoothing, and curve fitting.
• Also, the different seeding images have an effect on the processing sequences.
• To enable path-based edits, go to “expand” the trace, and then “ungroup”
the various paths.
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9. WHAT AUTO-TRACING
DOES NOT DO
• Automatic tracing does not make up for low-resolution image captures
(photos, scans).
• Automatic tracing does not fix original image focus…unless all that is
needed is a light line trace.
• Automatic tracing does not apparently create a total 1-1 raster to vector
trace of every detail (at least not on a desktop machine with the target
software).
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10. WHAT IS
AN AUTOMATED DIGITAL IMAGE TRACE?
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11. WHAT IS
AN AUTOMATED IMAGE TRACE?
• An automated image trace involves the following:
• A digital visual (whether born-digital or born-analog) is analyzed visually by
machine.
• Relevant lines are identified and created as paths.
• The tracing may be set to focus on particular aspects of the image based on
particular threshold requirements.
• The tracing that is captured will vary based on both the seeding visual…and
the type of tracing that is applied.
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12. SELECTIVE, REDUCTIVE, SUMMARY
• Image tracing often results in an excerpt or a summary of the original digital
visual.
• Image tracing captures and highlights a selection of the original image. It is
selective and reductive.
• In another sense, an image trace creates a new digital work derived from
the seeding image.
• The new (derived) work may be original in its own right, if it is sufficiently
“denatured” from the original. [However, in a legal sense, whether this is
sufficiently original in its own right will have to be determined by whatever the
legal context and through legal means.]
• The new digital work enables different capabilities for illustration, exploration,
styling, and other applications.
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13. SELECTIVE, REDUCTIVE, SUMMARY
(CONT.)
• The image tracing is reproducible and repeatable. Given the same seeding
digital visual and the particular tracing algorithm and the given tracing
parameters, the excerpted image will be the same as in prior versions.
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14. A GENERAL
AUTOMATED IMAGE TRACE SEQUENCE
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15. A GENERAL
AUTOMATED IMAGE TRACE SEQUENCE
1. Open digital image / digital visual (non RAW format)
2. Trace
3. Expand
4. Ungroup
5. Direct selection
6. Paths (specialized lines, curved, angled), anchors, fills
7. Process in-tool (Adobe Illustrator) as needed
8. Export (or save as) for further processing (may export as raster or as vector)
A. Need to export as .ai and such to maintain path editability
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16. IN ADOBE ILLUSTRATOR,
AFTER TRACE…CAN
• Recolor artwork
• Apply filtering effects (one-off or sequence)
• Edit
• Add layers
• Paint over
• Simplify
• Outline
• Mask / apply clipping mask
• Others…
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26. WHY TRACE?
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27. WHY TRACE?
• People are able to capture photographs at the micro, meso, to macro
levels. Think electron microscope images to galaxy-scale imagery.
• These images carry a lot of relevant information.
• Not all may be appreciated just with the naked eye and without further digital
explorations.
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28. WHY TRACE? (CONT.)
• Photos, though, are not capturable to particular ideal circumstances, in
some cases.
• Traces may clarify lines in cases of blur or low light or low contrast or other
challenges.
• Object selection may enable the capture of some select objects from a photo,
but traced objects may export in even clearer ways.
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29. WHY TRACE? (CONT.)
• Traces from photographs…
• may highlight particular aspects of the photos for analysis.
• may enable size comparisons of various depicted phenomena in precise ways.
• may enable illustrations, to convey particular select foci in the visuals.
• may seed manual illustrations [and provide manual drawing assistance for digital
drawing, digital painting, and other creative works (including artified and stylized
works)].
• may seed AI and other types of machine vision-based analyses.
• may enable new machine-created visuals.
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30. WHY TRACE? (CONT.)
• Illustrations may convey visual (and textual) information that is conceptual or
from the imagination.
• Traces from other works—photos, drawings, diagrams, and the like—may provide
faster starts to manual illustrations.
And others…
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31. WHY TRACE: FILE TYPES?
• Tracing enables saving out in vector (vs. raster) graphics.
• The .eps, .svg, and .ai files may be larger than the original raster, however.
.pdfs are more compressed (if optimized for Fast Web Viewing).
• The .svg format enables access to code for websites for the visual.
• The exported files in vector format are only 72 dpi in terms of raster effects
though.
• Vector graphics are highly scalable (vs. raster and bitmapping).
• There is transcoding between vector <-> raster.
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32. TYPES OF AUTOMATED TRACES
IN ADOBE ILLUSTRATOR 2022
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33. STRAIGHT TRACES (WITH COLOR
AND TEXTURE SIMPLIFICATIONS)
• Top-level “blue-line” trace
(depicted above)
• In the Trace dropdown:
• [Default]
• High Fidelity Photo
• Low Fidelity Photo
• 3 Colors
• 6 Colors
• 16 Colors
• Shades of Gray
• Black and White Logo
• Sketched Art
• Silhouettes
• Line Art
• Technical Drawing
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34. ORIGINAL DIGITAL IMAGE SEED
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35. HIGH-FIDELITY PHOTO
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36. LOW-FIDELITY PHOTO
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37. 3 COLORS
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38. 6 COLORS
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39. 16 COLORS
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40. SHADES OF GRAY
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41. BLACK AND WHITE LOGO
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42. SKETCHED ART
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43. SILHOUETTE
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44. LINE ART
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45. LINE ART TRACE ON LINE ART
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46. TECHNICAL DRAWING
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47. TECHNICAL DRAWING TRACE
ON A MAP
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48. TECHNICAL DRAWING
ON A TECHNICAL DRAWING
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49. “VIEW OUTLINE” AFTER TRACE
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51. SOME EARLY OBSERVATIONS
• It helps to have a “fit” between the original seeding image and the type of
scan that is run.
• However, cross-modal scans may provide opportunities for more artful outcomes
(in combination with filters).
• The background is usually an alpha channel (invisible or transparent layer).
This is a preference setting though.
• Trace scans can add structure to a diffuse visual.
• Trace scans can give an artful look to some of the seeding images.
• With words that are pseudo-captured in the scans, these are paths, not
recognizable font faces (that are machine recognizable). This is so with
word clouds, too.
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52. SELECTING THE TYPE OF TRACE
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53. SELECTING THE TYPE OF TRACE
• How to select what type of trace to use?
• Is the decision based on the original seeding visual work?
• Is the decision based on what sort of visual outcome you expect?
• It looks to me that both matter…the seeding visual…and the desired
outcome…
• It helps to experiment across a variety of seeding images and different trace
methods. This is a costly “brute force” approach, but given potential
variations, it helps to know what comes out.
• Do not restrict yourself to within-modal tracing. Experiment with cross-modal
tracing, too, such as using a photo for a line art tracing or technical drawing.
What results is ultimately what’s most important.
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54. HIGH VS. LOW FIDELITY
PHOTO TRACE COMPARISON
Same original photo as seed for both trace runs
High fidelity photo trace above
Low fidelity photo trace below
700 ppi visual
No image compression in PowerPoint (but compression in PDF)
Note the branches
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55. SOME PRE-PRODUCTION EDITS
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56. PRE-PROCESSING
• From RAW image transcoded to a sufficiently high-res mainline digital image
format
• Go fairly high-res (400 – 700 ppi), so the tracing has thicker spatial resolution
pixel data to work with.
• Sharpen the original visual.
• Change contrast for higher contrast.
• And others…
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57. SOME POST-PRODUCTION EDITS
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58. SOME POST-PRODUCTION EDITS
FOR QUALITY
• Edit paths
• Remove unnecessary paths
• Sharpen the traced visual
• Crop or select to emphasize particular regions
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59. SOME POST-PRODUCTION EDITS
FOR STYLING AND AESTHETICS
• Add line overlays (manual, digital, AI)
• Add highlights, midtones, shadows
• Add textures
• Apply filters
• Apply neural filters
• Change hue and saturation
• Change brightness / darkness
• Experiment with sequences
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60. SOME POST-PRODUCTION EDITS FOR
STYLING AND AESTHETICS (CONT.)
• Use guides to create a different visual (without the original lines)
• Use a visible grid
• Overlay multiple visuals
• Etc.
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71. CONTACT
• Dr. Shalin Hai-Jew
• ITS
• Kansas State University
• shalin@ksu.edu (email preferred)
• 785-532-5262
• Caveat: This work highlights some limited aspects of auto-tracing…but this is
not comprehensive. The use cases I show are of an instructional design and
“common art” type…which leaves out many other use contexts (research,
illustration, analysis, and others).
• The tracing capability has been around for years, but I am sharing this as
something new to me.
• About images: Images used here are original except for one open-source
visual (from Wikimedia) for the technical drawing example.
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