Creating Crisp, Smooth Line Art: Ian O’Neill

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Ian O’Neill is a self-taught artist who draw bright and colorful characters, often in weird and wonderful environments. His specialty is line art and illustration, from album covers to t-shirt designs to graphic design and even typography. We asked him to take all of his skills as an illustrator and teach people to make clean, crisp, powerful line art.  

Line art is an essential component of many art forms. From animation and comics to technical drawings and blueprints, all are technical skills with varying degrees of draughtsmanship. In modern pop media line art takes on almost limitless styles and forms, whether it be the super fine lines with fixed width of anime or the expressive fluid strokes associated with the western comic masters. In this tutorial I’ll aim to give you a little insight into how I create my line art using SketchBook Pro.

I don’t subscribe to the idea that there’s any right or wrong way to go about the process, so I’ll simply be explaining how I go about producing good quality, crisp and clean line art. Or at least attempting to! I’ll let you be the judge of that.

Sketching for Success: Getting Started

“A building is only as good as its foundation” — so some obscure historical figure probably said. The reason I bring it up is because it’s equally true of line art. The best, most skilled and expressive lines in the world won’t make an anatomically flawed mutant of a character sketch suddenly become good design. Now as this isn’t really the focus of this tutorial I won’t bang on about this, but I’ll provide a couple of simple tips to keep in mind when attempting to produce a solid sketch.

When I begin like this, I use a large and blurry brush preset similar to a crayon or marker pen so fine details are impossible. This is to stop me from getting too carried away on things like facial features.

Details are unimportant at the beginning as what we’re looking for is nailing the form, gesture, and the loosest of design details. With this in mind I always zoom in to at least 100% with a large canvas, so I’m only working a very small portion of the canvas that’s visible on my screen. When I begin like this, I use a large and blurry brush preset similar to a crayon or marker pen so fine details are impossible. This is to stop me from getting too carried away on things like facial features. You don’t need to see every buckle and button on your character’s clothing at this point! What you’re left with is essentially a thumbnail image when zoomed out. I’ll often do several of these, either variations on an idea or entirely unrelated and original ideas for style exploration. Once I have one I’m happy with, I’ll enlarge it to fit the final page size and composition until I’m satisfied, then use the crop tool to get rid of any excess canvas I don’t need.

I tend to spend more time on my chosen sketch working in quite a lot of design details, as I don’t like to be making it up as I go along when inking the line art. This varies from person to person. As long as the design makes sense to you, nothing else matters. I’ve always thought of sketching as visual shorthand, just like a writer uses to get ideas down on paper while they’re fresh. It doesn’t matter if it’s entirely illegible to anyone else (unless you’re handing your sketch to an inker), as long as you can make sense of it. There are no awards for Best Sketcher being handed out — not that I’m aware of, anyway.

Anatomy of a Line: Technique

Most people will tell you that smooth flowing lines are best created in one fluid motion, and they wouldn’t be wrong. An essential skill to achieve this is learning to draw from the shoulder, rather than the wrist. Obviously most of us have limitations placed on us by the size of the tablet surface we’re working on. A 24-inch device will allow almost a full arm’s stroke from left to right, whereas on my 12-inch Cintiq I can achieve roughly half of that.

Most people will tell you that smooth flowing lines are best created in one fluid motion, and they wouldn’t be wrong. An essential skill to achieve this is learning to draw from the shoulder, rather than the wrist.

No matter what size tablet you work on, the key is to zoom out only as far as you need to fit as much of the line you want to create on the screen in one stroke of the stylus. If you can’t make it in one go, try making the second stroke from the opposite end to meet in the middle. If both lines taper off (get thinner) it can result in a really appealing look where they meet. Here you can see the difference between those techniques. The two fluid strokes from the wrist and shoulder respectively look smooth and precise. Whereas, the two attempts to replicate these lines without fluidity in the stroke look… Well, frankly awful!

I personally rely on a combination of these long fluid strokes as well as shorter flicks of the wrist. I also use shorter, less-fluid strokes to build up the line weight (thickness) of the lines in places. More often than not, I’ll significantly thicken a line as it joins another as you can see in the example here.

This is a personal style preference and essentially just the way I naturally draw. But if you practice both types of stroke to perfection, you’re simply adding to your personal arsenal of skills, and it will only benefit you in the long run no matter what style of line art you gravitate towards.

The Technical Bits: Sizes, Settings, and Layers

Now I know one of the most exciting bits for a lot of aspiring artists is getting the lowdown on what special magical brush presets artists use to make the stuff look “so hawt”. Prepare for disappointment, people, as I use the most fundamental tool used by artists throughout history — at least, the digital version of it. The humble pencil is my weapon of choice. Yes, that’s right. The default Pencil tool in SketchBook is my go-to inking tool. I’ve made several custom tools and presets in the past, but I always come back to the Pencil. In fact it’s what attracted me to use SketchBook over many more well-known applications to begin with, and it’s what’s kept me using it ever since. In my opinion, there is no better emulation of using a real pencil for tablet users. It’s such a diverse tool and can be used to create a variety of line styles by simply varying the pressure applied or the drawing angle of your stylus. Despite that, I’d advise you try some of the many brush presets on offer and see what works best for you.

What’s more important to me than brush choice is the brush size in relation to the size of the canvas. I generally use a canvas of around 4000×4000 pixels at 300 dpi. For me that means using a Pencil at around size 8.5-9 for the majority of the lines. This means I can get a thick enough expressive outline, but with less pressure I’m able to produce finer more detailed areas. If I’m working on something for print I’ll size my canvas at the required print output, for example 8.5×11 inches at 450 dpi (a pretty standard comic page size).

Many printers have differing desired output, so make sure to ask in advance if you need a minimum size. High-quality printing generally requires files prepared at 300 dpi minimum, just so you know. If your work is only intended to be shown on the web, then make a consideration for the fact it will need to be scaled down. If your lines are too thin the web friendly version can look jaggy as hell, resulting in your beautiful fluid lines becoming some sort of deranged pixel art. Also when resizing, it’s advisable to resize by even increments, like 25%, 50%, and so on to avoid any pixel mishaps.

Lastly, I’ll create a New Layer on top of the stack. This will be our line art layer, so you might want to name it appropriately. Call it “Geoff” if you like (who am I to judge?), but something like “Lines” will probably be easier to make sense of at a glance.

Did you know that maths can help you understand document print size? This simple equation will help you know how many pixels you need on a screen to print at a certain size:  X (pixels) divided by Y (dpi)= Z (print size in inches).

Face First: Starting to Ink

Before you get stuck in, reduce the opacity of the sketch layer. This allows you to see your lines clearly on top. I normally go for about 20-25% opacity. Once you start inking, take advantage of your natural physical assets. What I mean is that everyone’s muscles have more control in a certain direction. For me, I can produce a near perfect quick straight line moving my arm up and right from my shoulder.

Knowing that, I can rotate the canvas to accommodate my strongest direction of line. It may seem time consuming to spin the canvas constantly at first, but trust me, it’s a lot quicker than redrawing that line you can’t quite get right 600 times.

As you can see, I pretty much always start on the outlines of the face and the facial features when working on characters. The reason for this is that in my opinion the face portrays 75% of the mood and personality of your character. A line here or there can subtly change the expression from “I’m determined” to “I’m on the warpath!”

With that in mind, I always feel that if I nail the facial features it sets me off on a roll and helps me get into the fabled zone. It also serves to get me warmed up for the feel of the line art as it uses several differing types of strokes: long fluid lines on the shape and outline of the face, then shorter more controlled strokes with the wrist on things like the eyes, nose, and lips.

Don’t stop and debate, always rotate! SketchBook’s all-in-one Pan/Zoom/Rotate makes it quick and easy to manipulate the direction of the canvas. Use it.

Weight of a Line: Thick vs. Thin, Out vs. In

Part of what creates the appeal in my lines (I hope it does anyway, or I’m wasting my life away) is the balance between a variety of line weights. People often compliment how clean and crisp my finished line art looks. This is probably because of my fascination growing up and spending time in blueprints, technical drawings, and diagrams. Most technical drawings and plans use carefully controlled variety in the thickness of lines to illustrate the difference between an external line (or edge) and an internal component.

I’m not suggesting for a second that you should all draw like robots, following rules for every design decision. In fact if there’s one criticism I constantly level at my own work, it’s that it sometimes crosses the line between expression (art) and technicality (function).

However, I do use the same simple rules to establish outlines to my character, a silhouette if you will. Again, it comes down to a style choice. Even heavier outlines can be added to the finished line art to alter the final appearance dramatically. Used well they can make a character seem to pop off the page! It’s all down to experimenting with what appeals to you.

Using a round or an oval brush when inking gives a vastly different effect. Try an ovular brush for a classic toon look, or a hard round brush with no pressure sensitivity for an anime appeal to your lines.

Check, Check, and Check Again: Progression

So as you can see I’m making pretty good progress now, working my way down from the face and starting to produce the overall form of the character.

Don’t be afraid to deviate from your sketch if something doesn’t look or feel right, or if it simply makes an improvement. In these situations it can be useful to hide the line art for a moment by clicking the small eye symbol on the layer in your layers palette and edit the sketch to reflect a change. If you’re confident though, this isn’t necessary.

As you progress, I can’t stress enough how important it is to regularly zoom out to see the full canvas and make sure your lines have the look you want. I frequently zoom out and hide the sketch layer for a moment to get a good look at my lines so far. I have the right touch strip on my Cintiq set to “fit to page” and “actual size” so I can easily do this on the fly without any faffing around. Remember to customize your tablet’s function buttons and SketchBook’s Lagoon settings (Cmd+<) to offer you the tools and commands you use most. It will save you time and effort spent taking your hands off the tablet fiddling with hot keys.

Map the shortcuts Cmd+0 (Fit to View) and Cmd+alt+0 (Actual Size) to your tablet to allow quick zooming in and out and stay in control of the overall appearance of your lines.

Inside Out… Lines: Depth Control

As I explained before, I often use a heavier line weight to define edges around my character. Well sometimes those edges aren’t on the outside of the illustration. If we use foreshortening, for example, a technique I use here to make the character’s hand appear to be reaching toward the viewer, the foreshortened arm and hand need to appear to be closer. I do this by varying the line weight; in this case a much heavier outline surrounds the hand and the small spherical drone (or Steve, as I like to call him). This creates an illusion of depth. Our brain reads the thicker lines as dominant, giving the impression of the hand and Steve the drone being further toward the foreground of the scene.

Foreshortening itself is a pretty intensive and thorough subject all of its own and takes much practice to get convincingly right. Trust me, I still balls it up quite regularly! But this simple technique of controlling line weights can be used in many situations to enhance depth, even in the flattest scenes.

Many top comic artists use line weight to dictate light sources as well, but I tend not to. Either I’m just not that skilled, or more likely, not that prepared for my color choices! Remember, some rules were made to be broken. Go nuts and experiment!

Thinner lines = further away. Thicker lines = closer. Due to the way our brains interpret light collected by our eyes, lighter colors recede when placed next to a darker color. So denser areas of black feel closer to the viewer.

Tablets and Tools: That Old Chestnut

I’ve lost count of the amount of times people suggested just using a ruler on your tablet screen to get nice straight lines. Whilst it works (sort of, if using a magnetic ruler to destroy your Cintiq is your thing), the nice people at Autodesk have decided to spare you the agony of gouging and scratching your very expensive tablet screen by including a full compliment of draughtsman tools. A ruler, scalable protractor (is that even a thing? Let’s just go with Circle Tool) and even a pair of French Curves make the simulation of natural traditional media a stress-free experience.

What makes these tools truly useful for the line artist is the fact you can still apply pressure dynamics on any given brush whilst using them. I always use these tools for geometric elements, even if I go over some parts by hand for stylistic effect. You can even use the erasers on them, which allows the easy manipulation of shapes cut out of your line art where necessary too. With some creative thinking it’s amazing how useful they can be. They are a vital part of my toolkit.

I use the Ruler tool for several straight line areas on the sword and the taut strap on the second image. The Circle tool makes light work of the drones and lenses of her goggles. I generally use these tools on any man-made, mechanical, or artificial objects that have perfect edges. Laying out a cityscape is a lot easier and faster with a ruler tool for example. (And even easier still using SketchBook’s Perspective tool.)

It’s All in the Details, Bub: Refining

As I reach the point where most of my character’s body and outlines are completed, I turn my attention to the finer details. As you can see, I like to add odd little suggestive elements of detail that a brain interprets as imperfections. It’s these imperfections that make a character slightly more believable for me. We can’t all be perfect and shiny in real life, so why should our fantastical characters be?

I also use smaller lines here and there to suggest creases, folds, and various other elements where it feels right to me. I’ll also draw in detailed aspects like the charm on the sword pommel, simply adding a heavier outline to them after they’re drawn.

To do this, I lower my trusty Pencil tool’s size down to somewhere between 2.0-3.5. Then I’ll give the whole piece a second pass and add any small details, sometimes even erasing details I had already inked with the larger Pencil and replacing them with crisper, finer detail. Remember when I said I thicken some lines where they join? Well now is another opportunity use this smaller Pencil to refine any of those joins or make any other changes. I should also add that I use the hard eraser on the minimum size setting of 2.0 throughout.

I also spot my blacks at this point, which basically means filling in any solid black areas. To do this I use the Paint Bucket tool. For this kind of line art I set the tolerance to somewhere between 40-80. It really varies depending on exactly how thick and dark your lines are, so a little trial and error is essential.

When zoomed in you can see that the fill leaves a slight pixel outline. I’ll just go over this with my pencil to make sure it’s a nice solid black.

You can see here that I wasn’t happy with her hair on the outside of her face. It’s essential not to be too precious about your lines at this point. If it doesn’t work or look right, don’t be scared to just erase it out or use the Lasso tool to highlight larger sections and hit the Delete key. If you’re unsure of how exactly it needs changing, create a new layer at the top of the layer stack and draw on that new layer first. Once you’re happy you can simply highlight the layer and select Merge with Below (Cmd+e). I also made some tweaks to her right eye, too.

The smaller the brush, the sharper and crisper its edges will look when zoomed out to final viewing size. Just don’t go too small, or you’ll get jagged edges if you reduce the image for the web.

Signed, Sealed, and Saved

My lines are all finished, and I’m pretty happy for a couple of minutes (before I start picking up on flaws or potential improvements, that is.). All that’s left now is to sign my work and get it ready for display. Those paying careful attention to this point in what has been an admittedly wordy tutorial will have picked up on the fact I’ve mentioned on several occasions about resizing and making sure your lines aren’t too thin. Well, here’s the moment of truth folks! First, I save my work before doing anything else. (I always save as a PSD; it gives me the option to open it in other apps should I need to.)

The final image is 3825×4047 pixels at 450 dpi. (In this case, just because I forgot to change the DPI value after the piece I last worked on. Doh!) To be suitable for posting on the various sites I frequent like DeviantArt and Tumblr, half the current size is ideal. So I’ll go to Image > Image Size and change the pixel values to percent by using the handy little drop-down menu, before entering 50%. Voila! My lines still look good, no distortion, and the finer details look even sharper as expected. I always save my web versions as a PNG, as it is a more lossless compression than JPEG.

I should add that it’s by no means mandatory to lower the size. It’s simply a necessity when it comes to posting on the web. The final line art will look just as good at full size as long as your lines weren’t too thin to begin with. But the rule of thumb is, draw on a big canvas, and you won’t be caught short later!

Life in Technicolor: Prep for Colors

I won’t be showing the process of coloring this piece as the main goal here is to focus on crisp line art and frankly, as I’ve far exceeded my word usage for the rest of the month already. However, being the utterly amiable chap I am let me just say a few words on how to easily prep for color.

Now that you have your finished lines you can discard any sketch layers bogging down the layer stack, unless, of course, you want to keep them for some reason. Create a new layer, making sure that it’s placed below the “Lines” layer (or “Geoff”). Now you can color underneath your lines. It’s really up to you to decide on what style of colouring you want to go ahead with.

I generally keep my use of layers to a minimum, normally three or so, as you can see here. I have flat colors, then a shade layer often set to Multiply (in the drop-down layer modes at the top of the layer stack). Then, I’ll add a third layer with any highlights, which, depending on the result I’m looking for, is normally on Overlay or Color Dodge. As I said, this varies from piece to piece. More painterly types may do everything on one layer, others may use a multitude of layers and techniques.

You can also color your line art (known as color-holds) by simply clicking the Lock Transparency button on the Lines layer in the Layer stack. It’s the one that looks like a little chequered padlock.

Experimentation is vital when it comes to colouring your line art, as there are almost limitless different techniques and styles to choose from. Personally I lean toward what most folks would call “cel-shaded” style art, which is probably a result of watching a lot of the media that’s inspired me over the years. You might like to try something completely different based on the art that appeals to you. Whatever route you go down, good luck!

Thanks for Reading

I hope this tutorial has been useful in some (any) way for you! Good luck with your line art and remember, try to learn from others but at the same time do what comes naturally to you. Over time you’ll find your own style and rhythm that might just be more appealing than those artists you aspire to emulate.

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