Krita has a unique feature to colorize line artworks quickly and easily called “Colorize Mask”. In this tutorial I will show you how we can use this feature. This tutorial will be divided into 2 parts. In the first part which is this one you’re reading we will cover the basics. And then later in the second part video I will explain more advanced techniques and tips.

Colorize mask tutorial video:

Colorize mask written article:

For start I already have a file opened. I have several layers here so we can practice using colorize mask right away. In the upper layer I have a line artwork of a milk box. And at the bottom I have a layer filled with a solid orange color.

Just for your information, this milk box drawing is actually part of a game project that I did back in 2015. It’s an educational game for kids where children can learn object association and the names in Arabic language. This is the actual final result of the drawing I created for the project.

Back then I had to do hundreds of these object drawings in a very short amount of time. I’m explaining this to you guys, so you understand that in the actual production environment, feature like Colorize Mask can greatly speed up our workflow and at the end increases the project’s ROI. Unfortunately back then, colorize mask is still not exist yet in Krita, so I have to rely on other more slower methods.

milk bottle coloring page
Milk bottle coloring page

If you want to download line artworks like this milk bottle, just so you have something to practice using the colorize mask feature, I just uploaded some of these in this website. Just go to the “coloring pages” section and download from there.


Before we deal with the nitty gritty of colorize mask. First let me explain quickly about the mask concept in general in Krita. You may already familiar with the mask concept in other graphic application. Mostly masks in other application are greyscale images that we can use to control layer’s transparency. In Krita however, mask is more than just that. Krita actually offers 5 different mask types and transparency mask is just one of them.

Essentially a mask in Krita is additional information that you can attach to a layer. So in it’s ideal state a mask should always be parented to a layer. You really don’t want to have a mask floating around without any parent layer, because in that state it will affect the whole image composition. I will discuss about different mask types more in depth in another tutorial in sha Allah. For now let’s focus on the Colorize Mask.

So by definition, Colorize Mask is a type of mask in Krita that we can use to add colors automatically to it’s parent layer.

Adding colorize mask

There are several ways to add colorize mask to a layer. First we can use the manual method and second the automatic method.

To do this manually, you need to make sure that you have your layer selected. I mean the parent layer of where you want to attach your colorize mask to. Generally this layer should be your line artwork layer. Okay. Then go to the bottom of the layer docker. Click on the caret button in here. And choose colorize mask.

Adding Colorize Mask manual method 1

We can see now this layer has a colorize mask attach to it. It is indented to the right a bit, telling us that this is a child of the line artwork layer and not an ordinary layer.

Colorize mask just added to the line artwork layer

We can use this button to expand or to collapse it.

Use this button to collapse and to expand the colorize mask

If you want to remove a colorize mask. Simply select it and click this trash icon button in here, just like how we remove any other layer or mask in Krita.

Removing colorize mask

Another manual way to add colorize mask is by right clicking on a layer and then choose “add”, and then choose “colorize mask”.

Adding Colorize Mask manual method 2

Now to add colorize mask automatically, we need to use a tool dedicated for colorize mask, called “colorize mask editing tool” which is this tool in here.

The Colorize Mask Editing tool

Now, you may have your tool at the left side by default. I just like to have them on top, just my personal preference. Okay, now after you activate the tool, next you need to make sure that the target layer is active.

Then notice the mouse cursor changed to a finger symbol. Just click on the canvas. And as you can see the colorize mask is created automatically for this layer which is great, but suddenly, we can see the pixels in this layer become blurry.

Colorize mask added but the image becomes blurry

Why is that? Well this is because we are now in the colorize mask editing mode.

Colorize mask edit mode

The colorize edit mode is the mode where we can add and remove key colors. To enter and exit the edit mode we can click on this pencil-like icon at the colorize mask in the layer docker.

The pencil icon is used to toggle on or off the editing mode

So this is one way to do it. Another way to do this is by opening the tool options docker. In the tool options docker you can see this check box “edit key strokes”. This is the option that actually turns on or off the colorize editing mode. It is the same as clicking the pencil icon at the layer docker. Okay.

The “Edit key strokes” checkbox can be used also to toggle the editing mode

Now to add color, first I would recommend you to use hard edge brushes, preferably those that doesn’t have any anti aliased effect. Why? Because it will be easier later if we need to erase or to edit them again. So I’m going to use this basic solid brush for the colorize purpose.

Pick a color, I’ll pick an off white color. And then just stroke like this.

Just repeat the process for all of the regions in the line artwork. After finished you’ll get more or less like this.

After adding key colors for each of the line artwork region

Okay, now that we have provided the key colors, we can then tell Krita to render the colors for us. To do this we can click the “update” button in the tool options docker, or you can also click this circling arrows icon in the layer docker.

Ways to render the colors

Now, Krita is calculating and filling in the rest of colors for us. It may takes several seconds or minutes to finish depending on the complexity of your line artwork. After finished, we need to exit the colorize mask edit mode to see the result correctly.

The colorize mask rendering result

Revising colors

The last thing we’re going to cover in this video is revising the colors. For example, let’s say we changed our mind and want to have the lid color in here to be red instead. We can do this by first entering the edit mode. Then we need to erase these color spots in here.

We need to erase these key color spots

For this we can use an eraser brush, or just use the previous solid brush preset but press E to activate the eraser mode. Then just erase these colors in here.

Erasing the previous key color spots

Press E again to turn off the eraser mode. And find the color we want to use instead. Then just like before add some strokes.

Adding the new color spots

Then click the update button to tell Krita to process the new changes. After it is done, we can exit the edit mode to see the final result.

And there you go, we just colorize a line artwork quickly and easily using Colorize Mask feature in Krita. Of course there are still more advanced stuffs that we need to cover about colorize mask and we will discuss that in the second part tutorial. Wassalamualaikum.