How to Add Beautiful Blur Effects to Your Digital Art in PaintTool SAI

As a digital artist, you know that subtle effects like blurring can take your paintings and illustrations to the next level, adding depth, atmosphere and polish. PaintTool SAI is a fantastic drawing program beloved by amateur and professional artists alike for its natural brush engine and streamlined interface.

However, if you‘re coming from Photoshop or another robust image editor, SAI‘s built-in tools for adding blur effects may seem quite limited at first glance. But fear not! With a little creativity and know-how, you can achieve stunningly blurred backgrounds, dreamy bokeh, and realistic motion blurs in PaintTool SAI.

In this in-depth tutorial, I‘ll walk you through three methods for adding beautiful blurs to your SAI artworks:

1. Using the native Gaussian Blur filter for basic blurring
2. Manually building up motion blurs with multiple opacity layers
3. Recreating the classic Blur Tool from SAI version 1 in version 2

Whether you‘re a beginner just starting out with digital painting or a seasoned pro looking to expand your PaintTool SAI skills, by the end of this guide you‘ll have all the tools and techniques you need to master the art of blurring in SAI. Let‘s dive in!

Method 1: Gaussian Blur Filter

PaintTool SAI does have one dedicated blur filter buried in its menus: Gaussian Blur. Here‘s how to find and use it:

Step 1. Open your SAI file and select the layer you want to blur.

Step 2. Go to Filter > Blur > Gaussian Blur.

Step 3. In the Gaussian Blur window, adjust the Amount slider to control the strength of the blurring effect. Check the Preview box to see the changes in real-time.

Step 4. Click OK to apply the blur to the selected layer.

The Gaussian Blur filter is best for adding overall softness to an image or background. The "Amount" value determines the radius or spread of the blur. Higher amounts will create a wider, stronger blurring effect, while lower values produce a more subtle blur.

One important thing to note is that Gaussian Blur affects the entire selected layer equally. There‘s no way to limit the blur to certain areas using this filter alone. To blur only parts of a layer, you‘ll need to either use a layer mask or resort to one of the other blurring methods we‘ll cover next.

The Gaussian Blur filter is the quickest and simplest way to add basic blurs in PaintTool SAI. However, it doesn‘t offer the fine-tuned control or range of options that more advanced blurring tools do. For that, we‘ll need to get a bit more creative…

Method 2: Opacity Layer Trick for Directional Motion Blurs

Let‘s say you want to depict a fast-moving subject, like a speeding car or a flying superhero. To sell that sense of speed, you‘ll want to add directional motion blur streaking out behind your subject.

While SAI doesn‘t have a dedicated motion blur tool, we can fake a very convincing directional blur using multiple copies of a layer at reduced opacities. Here‘s how it works:

Step 1. Select the layer with the object or character you want to add motion blur to.

Step 2. Duplicate this layer several times. The more copies you make, the longer the motion blur effect will stretch.

Step 3. Arrange the duplicate layers underneath the original.

Step 4. Select all of the duplicate layers and reduce their opacity to 20-30%. This makes them more transparent.

Step 5. Using the Move tool, shift each blurred layer copy a little bit in the direction opposite the one your object is moving in.

The slightly offset semi-transparent layer copies will blend together to create a trailing motion blur!

With this opacity layer trick, the length of the motion blur is controlled by the number of duplicate layers you create, and its intensity is determined by those layers‘ transparency amount. You can make the blur "trail off" by lowering the opacity of layers further from the original.

The main advantage of this method is the creative control it offers. You can make your blur go in any direction and even follow curves and arcs by rotating and transforming the duplicate layers. And since it‘s using normal layers, you can erase or smudge parts of each blur copy to sculpt the effect.

However, building up a blur this way takes more time and effort compared to applying a ready-made filter. It‘s best reserved for adding dramatic motion blur to individual subjects rather than an entire scene.

Method 3: Faking the SAI v1 Blur Tool in SAI v2

Long-time PaintTool SAI users may remember that version 1 of the software included a dedicated Blur Tool for smudging and smearing colors to create soft, hazy effects. Sadly, this handy brush didn‘t make the cut when SAI was updated to version 2.

But with a bit of ingenuity, we can recreate the Blur Tool in SAI v2 using the Brush tool‘s Blending Modes! Here‘s the recipe:

Step 1. Select the Brush tool and open the Sub Tool window.

Step 2. In the Sub Tool properties, set the brush‘s Blending Mode to "Lighter Color" and its Opacity to 100%.

Step 3. Also set the Persistence slider to 100 so the blurring builds up quickly with each stroke.

Step 4. Now simply paint with this brush over the area you want to blur!

The "Lighter Color" blending mode works by comparing the brush color to the colors already on the layer and only painting pixels that are brighter. Since you‘ll be painting with the existing colors that are already there, this creates a smooth blurring effect! The larger and softer the brush tip, the more it will blur.

The key advantage of using a manual blurring brush is that you can selectively apply the effect to any part of your artwork, blurring one area while keeping others razor sharp. A blur brush is perfect for adding atmospheric perspective to distant scenery, foggy halos around lights, or velvety skin and fabric textures.

On the downside, blurring with a brush takes more time than an automatic filter and requires a bit of finesse to apply evenly. It also only works on raster layers, whereas the Gaussian Blur filter can be applied to vectors and lineart too.

Blurring in PaintTool SAI vs. Other Software

Compared to fuller-featured image editors like Photoshop, PaintTool SAI‘s built-in blur effects are definitely more limited. SAI only offers a basic Gaussian Blur filter while Photoshop and others have a wide variety of blur tools like Box Blur, Lens Blur, Radial Blur, Smart Blur, Surface Blur, and more. These allow for greater precision and control over the blurring effect.

However, as we‘ve seen, it‘s possible to achieve many of the same blur styles in PaintTool SAI with some creative thinking. The opacity layer and custom brush techniques covered in this tutorial can replicate the look of most common blur filters effectively. And these methods actually afford more hands-on control compared to one-click filters.

Still, adding complex blurs manually is usually more time-consuming in SAI than in Photoshop or GIMP where blur tools are built in. If you find yourself needing to apply complicated blurs frequently, a more advanced image editor may be a better fit.

Personally, I like to do most of my drawing and painting in PaintTool SAI to take advantage of its lovely natural brushes and clean, focused UI. Then I‘ll save my artwork as a layered .psd file and switch over to Photoshop for more advanced effects and edits. To me this provides the best of both worlds – SAI‘s drawing flow plus Photoshop‘s extensive features.

Conclusion

By now you should have a solid grasp of how to create beautiful, believable blur effects in PaintTool SAI using:

1. The Gaussian Blur filter for overall softening.
2. Opacity layer copies to create directional motion blurs.
3. A custom blending brush to mimic the old Blur tool.

Each method has its own strengths and ideal use cases:

• Gaussian Blur is best for quick, subtle blurring of an entire layer.
• The opacity copy trick is perfect for dramatic motion blurs behind moving subjects.
• A manual blur brush offers the most control for targeted, painterly blurring.

Try experimenting with these different techniques to see which you prefer. Don‘t be afraid to combine them too! For instance, you might rough in a background using the Gaussian Blur filter, then go in with the Blur Brush to finesse certain areas and add selective focus.

With practice, knowing how and when to use blurs effectively will become second nature, elevating your PaintTool SAI artworks to new heights of beauty and realism. Just remember, when in doubt, keep it subtle – a little blurring often goes a long way!

Do you have any other tips or tricks for creating cool blur effects in PaintTool SAI? What do you think of SAI‘s built-in blur options compared to other drawing software? Let me know in the comments below!