Digital Inking

Creating pleasing looking line work on the computer can be quite a frustrating experience for artists who have come from drawing with pen and ink on paper. It’s taken me a few years of trial and error to get to the stage where I am happy with the line work I can now create in software. Since I’m sure many artists have had similar experiences to mine, I have written this article to share my experiences and hopefully help others who may be frustrated with this particular aspect of digital artwork.

It goes without saying that you need a Wacom tablet to follow this article. I am talking about hand-drawing lines over sketches, just like “inking” a comic book panel with a brush or a pen.

To keep things simple and get to the point quickly I am initially going to just discuss how various packages handle lines, and then I will discuss the more general aspects of each program later. I will also add some general thoughts on drawing on the computer. One package I will not discuss in depth in the first part of the article is Photoshop, for simple reason that I really don’t like using it for line work – it just doesn’t lend itself to creating pleasing lines, at least not in my hands. Photoshop does however excel at many other things, and I do use it for sketching, which will be discussed in more depth later on in the article.

I’m not sure what it is about Photoshop that doesn’t lend it to creating good line work, but all my attempts with it end up looking clumsy. I’ve tried various brushes, and sensitivity settings but the way the brush tapers and the flow of the lines never looks right.

Instead I am going to discuss three alternative packages that I have experience with, with specific reference to the quality of the lines that can be produced with each.

The first, and by far the easiest package for creating good lines is Illustrator. Even a relative novice should be able to produce very slick results with Illustrator.

Firstly you should place your sketch on a layer, lock it and create a new layer above it. This is where you will draw your lines. Select the brush tool:

If you double-click on the brush icon from the tool palette above you can control the behaviour of the brush:

You will want to disable the options to “Fill new strokes” and “Keep selected”. The Smoothness slider controls the amount of interpolation added to your brushstrokes, if you have shaky hands and poor control you can try setting a higher value to smooth out your lines. The drawback is that the lines might get too smooth and be less faithful to your actual drawing. A bit of trial and error should help you find your optimal setting. Bear in mind of course that you can always change this on the fly, for instance if you need to draw a long and difficult curve you could momentarily increase the smoothness setting to make it a little easier.

To set the pen pressure you need to use the Wacom drivers, I frequently use the buttons at the top of my Intuos II to flick between hard and soft pressure settings.

There is unfortunately no quick and easy way to rotate the canvas (you can manually rotate objects if you need to but there’s no really quick way to do it to the whole canvas other than set up an action). This would help with drawing awkward angles, but the smoothness slider can help to overcome this problem.

One great benefit of using Illustrator is that the lines are in vector format and can be edited at any time. If you need to make a little tweak to a line you can either select individual points along it and move them with the white arrow tool, or you can select the entire line and redraw all or part of it with the brush tool. This gives you a great deal of control and flexibility.

Here is a typical example of the kind of line work you can expect from Illustrator:

As you can see it looks quite slick and the pen responds well to pressure. You can set up various brushes, I use the calligraphic ones for simple pressure sensitivity but you can also use the art brushes for different effects. In the example below I’ve used an art brush to give a scruffy pencil feel:

With art brushes you can also set up other effects, like ultra-smooth paintbrushes with tapered ends (Disney artists use this), or alternatively really messy splattery brushes. The big drawback unfortunately is that the art brushes are not pressure sensitive, only the calligraphic brushes offer this option – and these can only be smooth so you can’t get the more organic effects with them.

Here are a few more examples of the kind of line work that is easily achievable in Illustrator:

The big problem with Illustrator is that the lines can feel a little too slick, and they can look quite computer-generated. This brings me to the next two options in this article.

To get a more organic feel a bitmap based program is probably superior to a vector based one such as Illustrator. The first of these that I am going to discuss is Corel Painter. Painter has a multitude of brushes to choose from but a simple Camel Hair variant under “oils” works very well for painting lines over a sketch.

As before it’s best to create the line work on a new layer above a sketch. There are numerous brush controls available in Painter but I am just going to discuss those that are most relevant to this article. The first thing you should do is go to Edit --> Preferences --> Brush Tracker and draw some strokes to set up the pressure response.

Next, with a simple Camel Hair brush here are the most important controls to adjust – you will need to have the Brush Controls panel open to adjust these:

The Size and Min. Size sliders control the variation of the brush’s width, I like to set the minimum size very low to get a nice variation throughout my stroke.

The Feature slider controls how many “hairs” there are on the virtual brush, the lower the number the thicker the brush. For best performance set this as high as possible while still retaining a solid line. Low feature settings can impact performance.

The Damping slider is similar to the Smoothness setting in Illustrator, it controls the interpolation of your brushstrokes. The higher the setting the smoother your strokes are, again setting it high can make the brush responsiveness much slower so try and find a good compromise. I find that the default 50% works very well but you can always temporarily increase it to draw a difficult curve.

You should notice straight away that drawing lines with Painter has a very nice feel, there is something highly enjoyable about the Camel Hair brush that is hard to explain until you use it. The lines flow beautifully and the variation in thickness is very natural, compared to Photoshop this is a million times nicer.

There are a few great features to Painter that are useful for this particular topic. Firstly it is possible to rotate the canvas (without actually rotating the pixels – this only affects the display) by holding down the space bar and then the alt key and dragging with the mouse. This is just like turning a sheet of paper when you draw to get a better angle for a particular curve. If you hold own space + alt again and just click the canvas it is reset to its original orientation.

You can also use one of the non-bleach based erasers to erase back to transparency on the layer you are working on (as far as I remember this didn’t work in older versions but with version 9 it now does). This is a great way of refining your lines by erasing back into them and giving them more life and expression, as well as correcting mistakes of course.

In Painter 9 it is possible to constrain your brush to a pre-drawn path, which is really useful if you have a very difficult long curve to draw.

As there are no keyboard shortcuts to access different brushes it is a good idea to set up a custom palette with your favourite brushes so that you can have rapid access to them.

Here is a sample of line work done with the camel hair brush in Painter:

The lines have a natural look to them and look more organic than those created in Illustrator. The results are still quite slick, and require only a little more drawing skill to achieve. There are so many options to control the response of the pen that most people should be able to get decent results with a little practice.

There are of course many other options to explore in Painter, and different brushes you might use – I’ve just scratched the surface here but it’s enough to get started with. There are some people for instance who like to use the Liquid Ink brushes for line work, however I find the Camel Hair brush more to my liking – this is a personal thing and it’s well worth trying out a few options before deciding which is best for you.

The next software I would like to discuss is Alias Sketchbook. This is a very simple drawing program that has a much more limited number of brushes and controls than either Painter or Illustrator. It has the basics, including layers, and is very direct and easy to learn. Painter can overwhelm with the number of brushes, options and controls it offers and takes quite a long time to learn, whereas Sketchbook can be picked up in half an hour.

As in Painter, you will need to set up your pen’s response to pressure, this can be found under Edit --> Pen Responsiveness.

To get going in sketchbook you need to open your original drawing and then create a new layer above it. Then select the brushes icon from the toolbar:

Drag the mouse on to the brush palette:

Which opens up this window:

Select a brush and click “Copy To Custom”, which takes you to the Custom tab:

Select the brush you just copied and click “Edit”. This brings you to the brush editor where you can change the size and minimum size as well as a few other basic controls.

You can leave this window open while you paint, so that you can make changes to your brush on the fly rather than go through all those steps again.

Sketchbook actually has the nicest feel of all when it comes to drawing lines. There is no adjustable damping control, unlike the other two programs discussed here, but the programmers at Alias have definitely got the feel just right. In terms of tactile enjoyment it is the best drawing software I have ever used.

This sample was inked using Sketchbook:

It looks similar to Painter, although it is a little more natural still (less damping probably) and the slight wobbles that occur actually enhance the hand-drawn quality compared to the smoother results from Painter. It really looks like ink from a brush to my eyes, and it feels like it too when you are drawing.

Sketchbook doesn’t have Painter’s ability to rotate the canvas as you draw, however there is a menu command that will rotate the entire canvas in 90° increments. This is different to what Painter does since the actual pixels are rotated, but since the increments are fixed to 90° there is no impact on image quality (no interpolation takes place). It’s not quite as good as Painter in this respect but it’s still usable.

Another great aspect of Sketchbook is that it is a lightweight application, it launches fast, is very responsive and has a small memory footprint. This of course comes at the price of features and ultimate control over your settings, but what it does is pure drawing and it does that well.

There are however a couple of major problems with Sketchbook, biggest of all is its very poor integration with Photoshop. Whereas Painter and Illustrator will export layers and transparency to Photoshop Sketchbook won’t. The only file format in Sketchbook that allows you to save in layers in TIFF, and sure enough that works well within Sketchbook itself, however if you open the TIFF in Photoshop the image will be flattened. The same happens with transparency, even if you save as a PNG the transparency information is lost when you open the file in Photoshop.

For transparency there is a workaround, which is to open the file in Photoshop, copy and paste the image into a new channel, invert the new channel, create a new layer, load the channel as a selection (control-click on it in the channels palette) and fill the selection with black. You can then delete the background layer, your new layer will have the image on a transparent background. I’ve created myself an action to go through this tedious process automatically. This only works with greyscale images though, for colour you need to make a proper cut-out which will take a lot more time.

Although Sketchbook is my favourite application for inking images digitally, I feel that Painter probably makes a better recommendation since it is a much deeper package with a truly amazing feature set – one that will take you years to learn. In terms of feel and results it is only a little bit behind Sketchbook (and this may well be down to personal taste).

Sketchbook is obviously the cheapest of the three packages, but I actually feel that it’s a little overpriced considering the very basic features it offers and the lack of integration with Photoshop. Painter is available for $299 compared to $179 for Sketchbook but Painter is a much more powerful package. It is also possible to find older versions of Painter on Ebay at bargain prices, I bought a genuine copy of Painter 6 for £60, complete with all packaging and manual. If you are looking at older versions I recommend version 6, which is my favourite prior to 9.

One thing to bear in mind is that to achieve decent results in any software does take some drawing skill, this is not a case where the computer does anything for you – you need to be able to draw well in order to achieve good results. However, for those who are not so confident in their drawing ability Illustrator is an excellent place to start as it is very forgiving of mistakes or shaky hands.


Update: Liquid Inks in Painter:

I've been doing a little more experimenting with Painter, the Liquid Inks are interesting because they have more ways to control the randomness and blobbiness of the strokes, making them more natural and organic.

Here is a screen shot of the Liquid Ink controls:

The five sliders at the bottom all add some randomness to the strokes, giving a lot more variety to their appearance - in contrast to the other brushes in Painter which only have one slider to control jitter.

I thought it might be interesting to try and emulate some traditional illustrations that featured strong line work with the Liquid Inks to see how closely they can mimic real inks - the results are very impressive.

First up I copied a drawing by an french comic book artist called Franquin, he used a brush with ink to create his flowing lines - I think my version is a pretty good replica of the look of indian ink with a brush:

More challenging in theory for a software package is this copy of a famous nib pen drawing by Ronald Searle, the Liquid Inks in Painter were easily able the match the scratchiness of the original:

Finally, I also wanted to try out the rotring/stiff pen look. This one is the easiest to do in Painter, based on a drawing by Moebius, another french comic book artist.

The originals for comparison:

Also, another very intersting feature of the Liquid Ink brushes in Painter is that they can be resized to any size (as long as the file was saved in Painter's own RIFF format), here's a huge enlargement of the first drawing:


Some general points about drawing on the computer:

I personally now do all of my drawing straight on to the computer, for various reasons but the main ones being flexibility and speed. I actually do my sketching in Photoshop, although I don’t like it for inking it is actually great for straight sketches.

In Photoshop it is quite easy to set up a brush that feels like a pencil, and it’s very handy to have the brush and eraser on different keyboard shortcuts (b and e respectively). With the configurable tool presets and some custom actions and shortcuts it is possible to have different brushes set to different keys. I also have my Wacom pen’s pop-up menu set up so I can access my favourite brushes and painting modes quickly:

This kind of control makes Photoshop very efficient and fast to work with. Alongside the very comprehensive selection tools and image manipulation controls, it is a very good drawing application. I prefer it for sketching over both Painter and Sketchbook because it is more flexible, for instance if there is a hand slightly out of proportion on a character I can just lasso around it and hit control + t to scale it. You can move bits around, flip, rotate, distort etc… This sort of functionality is completely lacking in Sketchbook, whereas in Painter it is there but not as fluid.

Photoshop also lets you rotate the whole canvas losslessly at 90° increments if you need to draw at an awkward angle (although for sketching I rarely need this). All of the applications discussed let you mirror (flip horizontally) which is very useful for spotting mistakes.

Sketching in Photoshop allows me to draw very fast, and the complete edit-ability makes the drawing feel very fluid, the end result being a better drawing since making changes is effortless. Working straight onto the computer also saves time by not having to scan, which can amount to a considerable time saving if you are doing a large number of roughs for a job.

Painter and Sketchbook also have very nice sketching tools (and both have default pencils which work well, whereas in Photoshop I had to create my own). If Sketchbook had the ability to lasso and move bits of the drawing around it would be a lot more powerful. Painter can do this but it doesn’t do it quite as well as Photoshop does. Along with the lack of keyboard shortcuts this is what makes me favour Photoshop for sketches. Bear in mind that Painter does have custom palettes, so I would imagine that for some people these differences might not be important and Painter might work better.

Finally some sketches from all three applications, these were done in Photoshop:


These next ones were done in Painter:

And finally this one was done in Sketchbook:

Essentially drawing on the computer is no different to drawing on paper, once you get past the initial learning curve. My clients would generally assume that these roughs are done the old-fashioned way unless they are told different – and at the end of the day the process is not that important, it’s the results that count. The computer gives advantages of speed and flexibility, which is why I use it. At the end of the day it is still just drawing.

Initially the feel of the tablet does take some getting used to, looking at the screen rather than your hand is one problem, the slippery surface is another. Both these things can be overcome with practice though, a few weeks of perseverance is all that’s needed.