Easy Paint Tool SAI

One invaluable program in my repertoire is a strange little painting tool from the land of holographic pop idols and gameshows that hit guys in the balls: Japan. Unlike American comics, which take their time inking with heavy, shapely lines and large pools of black and color panels to make pictures readable, Japanese manga is generally done in black&white and is hundreds of panels long, and since no color will be applied requires a very fine attention to creating thin, perfectly readable line art quickly. Drawing these lines is an incredibly difficult and arduous process – one that aspiring artists go to school to master and then do for years tracing over a manga artist’s sketches before ever dreaming of drawing something of their own. Sound like fun? Nope. In comes Easy Paint Tool SAI, an awesome line art tool from tiny developer Systemax, who apparently still exist, but you could be fooled by their website. It may not compare to the professional hand-drawn techniques used by manga artists and their tireless teams of assistants, but thanks to a few ingenious tools, it can provide editable, pixel perfect line art quite quickly and much more easily than other vector-based art programs.

As far as I can tell, the software has never been officially translated into English, and even the website’s English is spotty at best. You can easily download a fan translation though, with the bonus of having the software unlocked, but it’s not that expensive and I hope you’ll purchase a legal license from the company for the $60 or so it costs now… even if you can’t actually ultimately use the legal, Japanese version… o_O;; After loading up you’ll notice that the interface is relatively simple compared to other paint programs, and while there are some advanced tools such as different types of brushes (crayon, acrylic, watercolor) and brush shapes, density settings, stroke/pressure stabilization, etc., I won’t be going into those today. What we’re concerned with are the linework tools.

First thing to do after getting your sketch scanned and set up how you like it (you can do that in Photoshop/Gimp/Painter etc. and import, or just do it in SAI, it’s perfectly capable) is to click this awesome “New Linework Layer” button right here. This grants you access to a Pandora’s box of usefulness. I’m going to start with a quick sketch of Keep I did for one of a series of polaroid pictures that will scroll during the ending credits of the game.

Now you’re presented with the totally awesome linework tools. The ones you’ll want to master are as follows:

  • Curve –  Probably the most useful drawing tool ever made and for some reason not in any other painting program that I’ve found. Curve behaves something like the pen tool in Illustrator but doesn’t require you to worry about handles. It does that on its own. Simply trace along one of your sketched lines placing anchor points along the way. Because there are no handles, you need to place more of them, but they will handle the curvature themselves. Pro Tip: If you misplace one, simply hold CTRL and you can drag it around and reposition it, all the while the curve updating in real time. 
  • Line – Operates the same as Curve, but adds no curve. A continuous line with hard corners. Curve will attempt to add curvature between all points, so if you need to create sharp corners, you’ll have to put two points very close together. Thus for rectilinear shapes Line is often better.

  • Weight – Changes the weight, or thickness, of your line. Easily get different thicknesses for different levels of detail. In general, outlines of main objects should be the thickest, and line width should decrease as detail increases.
  • Pressure – My favorite tool and the one that really makes SAI ingenious. Pressure allows you to adjust the percentage (0 – 200) of a line’s weight (see above) that a particular point on that line uses. This is how you take your lines from boring, uniform curves to shapely, beautiful linework. I’ll speak more in-depth about this one below.

  • Edit – The one quirk SAI has is that its editing and transformation tools are a bit awkward at first. At first you’ll have to switch to the edit menu to select/deselect points, move around more than one at a time, combine points, etc. But notice those little descriptions underneath each one? Yup, they’re all hotkeyed, and are super quick once you memorize all of them. Pro Tip: In order to transform, scale, rotate, and do other common things to groups of points, select them, then switch to the Selection Tool – the dotted box in the top left of the tool area.

The other tools I don’t use as often, but you may find you like. Pen operates much as the pencil in other applications, but creates anchors along the way. Eraser erases, and color changes line color. And to be honest, I’m not even sure what the Select and Deselect tools do. I’ll figure it out someday. But for now, on to actually making something!

My first step is to find a line weight I like for the “standard” weight I’ll trace the whole picture in. This’ll depend on the size of the image you import and what overall level of detail you want. For this picture I liked 8pt as a standard weight. I went through and traced the whole picture with the Curve tool, except for the box and rope, for which I used the Line tool, since it’s square. You can do these with the Curve tool if you like, but you’ll have to put two anchors very close together at the sharp corners, which makes it more difficult to edit later.

Kind of boring, huh? Don’t worry, it gets better.

Next I adjust the line weights to make the important areas pop more, and the details go into the background a bit. I play with weights of 6, 10, and 12. Notice how Keep’s hair, boots, and the snake are the thickest to accentuate them the most. Small details like her knee, nose, collar bone, fingers, and seams on the box are very thin so they don’t draw so much attention.

A bit better, but still boring. But next is the fun part!

The finishing touch and what really completes the line art is the Pressure tool. Now you get to go through and make each line look perfect, rather than dull and uniform. It seems a bit random at first, as you may not know which points to make heavier and which to make lighter. But I’ve found that the general rule of thumb is to imagine what’s separating one side of the line from the other. For places where clothes touch skin, for example, imagine where the clothes would be the tightest. These areas should be the thinnest, while the looser areas should be thicker. Similarly, for separations from the background, areas where the light hits hard and directly usually look best thin, while hidden, shadowed areas are thicker.

Here I’ve started applying pressure differences to Keep. Her hair is hit by the light on top, so the lines are thinnest up there and get thicker on the way down. Her headband has the least separation from her head/hair at the forehead, so it’s thinnest there. Other times the correct pressure is fairly clear, as in her hair part and eyelashes. The part in her hair fades to 0% to make a nice point, as do her eyelashes. Continue going through your drawing until you’ve completed this step, and then zoom back and check it out.

Much better! Now that the lines have shape they’re much more interesting to look at, and the picture greatly benefits from it. From here, you can continue to paint in SAI, as it’s a perfectly competent painting program as well. But I still generally import into Photoshop since there’s so much more you can do.

Whether you end up using SAI as a full paint program, or just for its mind-blowing linework tools, it’s an awesome little program. Give it a try!

(Pro Tip: Wondering what that grey blob in the top left is? Well just imagine who’s taking the picture…)

16 thoughts on “Easy Paint Tool SAI

  1. The tool isn’t actually unlocked by default. You still do need to buy the license at the end of the 31-day trial.

    • You’re welcome! :D The Edit options are a bit strange. Basically you need to go in to “Edit” mode so you can select points (or you can simply hold ctrl to select). Once they’re selected, you can perform operations like translate, join, deform, duplicate, etc. by clicking the check button next to that option. But! If you’re using keyboard shortcuts you can perform all these operations with hotkeys. It’s much quicker. For example, ctrl+click and drag to select two points, ctrl+click on points to translate. And so forth :)

  2. This was so good! Now I know what that Weight tool means! No wonder it doesn’t create line when I tried to… it changes thickness of the existing line! lol silly me. This was very helpful. ^O^ I just recently started using this SAI for linearts… I’m so happy to find this blog.

    • Great! Happy to be of help. SAI is great for line art, and with the pressure and weight tools you can make some really professional looking art. I’ve been using it almost exclusively recently, because its painting tools are great too. May write about them soon! :)

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