Know the Basics: Krita Part 2: Brushes, Masks and Filters
Welcome to the second of three tutorials focusing on the Krita basics. In this tutorial I will get you familiar with some of the advanced settings, show you how to create new brushes, and how to use the masks and filters that come with Krita.
Step 1. Configuring Krita - Windows vs. Tabs
As in many graphic programs in Krita you can work with multiple files simultaneously. If you try to open more than one you will see that the default setting for multiple windows is set to "tabs". This means only one file can be visible on screen while the other one is hidden. You can only toggle between them by clicking on tabs that are visible at the top of the screen or by pressing ctrl+tab. If you like to work with windows that can be visible simultaneously or dragged and scaled separately you need to go to Settings>Configure Krita>General>Window and from the Multiple Document Mode drop-down menu choose Subindows and accept changes.
Step 2. Advanced Brush Settings
Every predefined brush can be edited in many ways because there are multiple settings that control how they behave. To edit the advanced Brush Settings you need to click on the Edit Brush Settings icon in the top toolbar while the brush tool is selected. This will open a window with many options and settings. This may feel like a lot at first but the idea is pretty simple. Each of the brush engines has its own particular settings that can be adjusted. If you click on each one of them you will see that brushes on the top change and the settings on the left do the same.
For example: the most commonly used brushes are probably pixel brushes. The settings are grouped into "General" 'Source" and "Texture". Each group consists of different settings but most of them, except perhaps for "Brush Tip", "Blending Mode" and "Pattern" operate in a similar way. An example would be "Opacity". Here you can choose the default maximum value, whether you want the setting enabled at all and what the opacity is going to depend on. Most commonly, opacity depends on pressure but you may want to set it for example to "Fuzzy Stroke" or "Fuzzy Dab" to achieve some interesting effects. Each of those settings can be further controlled by a curve. When the opacity is set to pressure you can decide how sensitive your pen will be. In the printscreen you can see the same curve shaped in two different ways. The one on the left would make the pen very pressure sensitive while the one on the right would create an opposite effect.
Step 3. Creating a new brush
The easiest way to create a new brush is to save a default brush under a new name and then play around with the settings. Usually its better save under a new name first before making any changes to settings, just to avoid any confusion. To do it you need to change the default name to one of your choosing and click "Overwrite Preset". As you change the settings of the new brush you can check the effects of what you're doing on the right hand side. The top part of that window is reserved for an icon that will later represent your brush and help you find it amongst other brushes. You can use it to create your own or use the existing icon. If you happen to have painted over the icon or accidently cleared the whole window you can recall the icon assigned to this brush by pressing one of the icons below the testing area - called "Fill preset area with current icon". The other 3 icons are "Fill area with gradient", "Fill area with background color" and "Reset area to white". Don't forget to click "Overwrite Preset" every time you apply some changes. Once you switch brushes you might lose the changes (you can partially avoid it by checking "Temporarily Save Tweaks To Presets" option).
Step 4. Advanced Color Selectors
The Advanced Color Selector is one of the more popular ways to choose colors. In Krita you can decide what you want your color selector to look like. To do that you need to click on the icon in the top left corner of the Advanced Color Selector docker. This will open a window that will allow you to choose the type of color selector, color model or even change the color space to a different one from the color space your image uses (for example you can have a greyscale color selector in a RGB image).
Step 5. Adjust filters
To find all adjustment filters you need to go to Filter > Adjust in the top drop-down menu. If you use any of those filters on a layer they will affect it permanently. However there is another way of using adjustment filters as layers and you can turn them on and off. You can choose them by selecting "Filter Layer" from the drop-down menu on the Layers Docker. These Filter Layers will affect all layers below them. If you would like a filter to affect only one layer, select that layer and choose "Filter Mask" from the dropdown menu. This will create a filter mask that will only work with that particular layer.
Step 6. Masks
Masks are generally "extra layers" that transform the appearance of the layer they're attached to, and the effect they provide can be switched on and off. In Krita you can choose from three types of masks: Transparency, Filter and Transform Mask. All of the masks can be accessed from a drop-down menu on the Layers docker. The most commonly used one is the Transparency Mask. The way this one works is by creating an invisible mask attached to the layer that determines which parts of the layer are opaque and which are transparent. The mask is basically a greyscale image where black translates to 100% transparency and white to 100% opacity. You can paint on this invisible layer the way you would paint on any other layer. At this time your advanced color selector will turn into a greyscale mode. In the picture below I placed the mask image right next to the layer it's controlling to give you an idea how it works.
Step 7. Selection Tools
There are seven different tools that are available in Krita's Toolbox. Five of them are pretty similar: they help you select a desired area, the only difference is the way you can do it. These are Elliptical, Rectangular, Polygonal, Outline and Bezier Curve Selection Tools. The other two are color based selectors. The Contiguous Area Selection lets you select a color (and colors similar to the picked color) within an enclosed area. The Similar Color Selection tool will select the chosen color (range of colors) on the entire layer. To quickly deselect all you can click Ctrl+Shift+A.
Step 8. Transform Tools
There are three transform tools in Krita: Crop, Move and Transform a Layer or a Selection tool.
While the first two are easy to understand, the Transform a Layer or a Selection tool is more complex. When you have it selected, in the Tool Options docker you will see 5 ways in which you can transform your layer or a selection: Free, Perspective, Warp, Cage and Liquify. The best way to discover what they do is to play around with the settings of each one.
Step 9. Scaling Image
Scaling the canvas can make your image smaller or bigger, however it's important to remember that you may lose quality if you go from smaller to bigger. It's usually advisable to go from bigger to smaller. The way to scale your canvas is to choose Image > Scale Image to New Size from the top menu. A window will appear where you will be able to choose a new width and height for your picture (in pixels, centimeters, inches and so on.). If you want the picture to be transformed proportionally make sure you have the "Constrain proportions" checked.
Step 10. Resizing Canvas
Although it may seem like almost the same thing at first, Resizing Canvas and Scaling Image are not the same. With scaling you take an existing image and make it smaller/bigger while constraining proportions (or not), with Resizing Canvas you are not touching the image itself instead you add or subtract areas of canvas. To do this you need to chose Image > Resize Canvas. A new window will appear. You can change the width/height of your picture (in this case I changed the width from 744px to 1200px) and also choose the anchor (depending where you place it the width will be added on both sides, on the left or on the right).