With the success of the smartphones and tablets, digital graphical and painting activities become more popular. Besides watching videos or editing pictures, painting can be considered as the most creative activity on mobile digital devices.Digital painting brings to us numbers of powerful tools and features. Many digital painting techniques don’t exist in traditional painting art. We can see lots of digital artists creating incredible artworks, with awesome effects and colors.Starting on personal computers creations, with the booming of mobile digital devices (smartphones and tablets) digital painting becomes now more and more popular amongst artists, designers and art lovers. Painting applications running on mobile devices become more versatile, and also more powerful.Besides basic painting applications for kids or absolute beginners, high quality professional applications can be found on the market. The professional application level must offer more options and features to the users. But with more options and features, the applications become more sophisticated and more complicate to use.In this article I’ll talk about the topic which I do consider to be the heart of painting applications: the brush effects. I’ll not enumerate the thousands different models of brush heads. In fact I’ll try to explain how they work and how they are organized. Then how you can take advantage on mobile digital painting. THE BASISBasically, it’s easy to understand the mechanism of a brush stroke:1/ Take a basic image, like a circle.2/ Then print it once on the screen: you get a printed circle.3/ Following a straight line, print the image several times: you have several lined up circles. The spaces between the circles is still large.4/ Now close up the circles until they overlap each other: finally you get a straight line… made with circles. MORE OPTIONSOn the base of the brush stroke made with circles, we can add some variations of its aspect:1/ The size: many applications give the possibility to adjust the size of the brush with a cursor (or any other suitable tool). You can also find some applications, for a reason of simplicity, preset all the brush sizes, then the user cannot adjust them, but can select between several preselected brushes according to their size.All the 2 solutions have its advantages, it’s a question of developer’s choice. 2/ The opacity (color saturation): this parameter will add or remove transparency to the colors. To fade out a color, you just add more transparency. And with 0% of transparency, the color is totally opaque (100% saturation).3/ The space between 2 brush heads: this parameter can get you confused with the opacity adjustment. In fact, visually opacity and spacing produce the same effect, but they are totally different. Why spacing produce opacity? If you overlay several low-density images, you’ll obviously obtain a darker image. In the other hand, if you increase the opacity (saturation) of a low-density image, it darkens too.Practically, according to the wanted effect, you have to find the correct balance between opacity and spacing. If you want more transparent colors, spacing adjustment can be done first, then add or remove opacity. Just keep in mind that adding opacity will remove the transparency of colors.Just one more remark about spacing: the more you overlay the brush heads, the more image duplication you’ll get, and the more your device will slower down. It’s mechanical. Then sometimes you’ll find some sophisticate brush style drawing with a lag behind your finger.To summarize this, the best procedure to manage the brushes is to adjust orderly the 3 parameters: first adjust the brush size, second select the spacing rate, third choose the opacity. BRUSH FLUIDITY.The best way to make the brushes less responsive is to adjust the spacing at the smallest size. Indeed, the worse brush setting is: opacity and size at maximum, spacing at minimum. Then low speed and high darkness are guaranteed.But a too small brush size is not always best for fluidity, it depends on the form of the brush. Each user will find his own adjustments. Personally I feel more comfortable with a light but fluent brush, even with a big sized one. I prefer to make several small strokes than a large one. BRUSH STROKES QUALITYAll painting applications don’t have the same quality of brush strokes. A brush stroke can be defined by 3 particularities: responsiveness, smoothness and dynamic brush head effects.1) Responsiveness: is the short delay between the finger speed and the painted stroke on the screen. On the same device, two applications can have two very different speeds of brush strokes.2) Smoothness: there is an easy test you can make. Open your painting app, take a brush or a pencil, and quickly draw a circle on your device’s screen. With low quality painting applications, the strokes will show broken lines, like a train running inside a curve. These broken lines will disappear when smoothness is added to the strokes.3) Brush heads: all brushes don’t have the same optical effects. These effects are created by 2 elements: the form of the head, and the dynamic effects. These 2 elements could be added one by one or all together.In fact, brush heads are not only made with simple shapes like circle, square, triangle… Their forms are very rich and various.Brush dynamic effect is about the quantity of color loaded in the brush and the different movements given to the brush in the same single stroke (example: the jitter effect which throws the brush head at random over and below the line of followed by the stroke).All these advanced particularities make the difference between low quality painting applications and the professional ones.Artists always create their masterpieces according to the technical evolution. You can see the differences between drawings made with pencils and chalks. The techniques came first, giving more power and possibilities to artists.Digital painting on PC is widely used by artists and professionals. And now the mobile digital painting is starting strongly, it’ll surely become the next painting technique to master absolutely.