Beginner's Guide to Gradient Maps

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This tutorial was created as a collaboration between Esra (https://profile.clip-studio.com/en-us/profile/362yzkvzw-o8) and me (Toffl) for one of this month's topics, "Color Correction". Specifically, we're gonna talk about gradient map correction layers and cover all the most important things about them – what they are, how they work, how to use them and how to create gradients. Gradient maps are an extremely versatile tool, so even in this tutorial we only scratch the surface of what's possible.

We've also turned this tutorial into a youtube video – both the video and text version cover the same topics, so choose whichever you prefer. (The video is in english with english subtitles.)

Now without further ado, let's dive right into it. But before we can actually talk about gradient maps, we first need to clarify what a correction layer is, and why they are so useful.

Correction Layers

First off, what is a correction layer anyway? To put it simply, a correction layer applies a certain effect to all layers below it. What exactly it does depends on the kind of correction layer you choose. And the great thing about them is that they are non-destructive. That means, you can reverse the effect, or edit its settings at any time.

You can create a correction layer by right-clicking the layer palette, then in the context menu there'll be nine options to choose from under "New Correction Layer".

For almost all correction layers, a dialog box with customizable settings will pop up (which we'll ignore for now).

The correction layer itself will look something like this:

Where you would usually see the contents of a layer is a completely gray box, with a small icon in the corner. The icon indicates which type of correction layer it is. For every new correction layer, a mask is automatically created as well.

You can double-click the gray box at any time later on to adjust the settings, which will open the same dialog box you've seen when creating the layer.

 

 

Next up, what can all those different correction layers do? Here's a short summary:

First, Brightness/Contrast; as the name suggests this effect is able to change both brightness and contrast of the image.

Hue/Saturation/Luminosity can adjust – well, you guessed it – the hue, saturation and luminosity.

The Tone Curve effect adjusts the image's RGB channels using control points on a graph.

Level Correction is very similar to tone curve, but it uses sliders on a histogram instead.

The Posterization effect reduces the amount of colors in an image to a set number.

Reverse Gradient inverts all colors. (This is the only effect that doesn't have further settings.)

Color Balance lets you adjust the balance of each RGB color.

And Binarization turns all colors in the image pure black or pure white.

But all these correction effects pale in comparison to the magnificence of gradient maps. Gradient maps are probably the most complex of these nine and, more importantly, my favorite. That's why we created an entire tutorial dedicated to this one correction layer.

Gradient Maps: What they are and how they work

A gradient map is a simple yet versatile tool to change the colors of an image, for both grayscale and colored images.

Just like any other correction layer, you can create a gradient map layer by right-clicking the "Layer" palette, clicking "New Correction Layer" and then "Gradient Map". After doing that, the following window will pop up:

At the top you see the color bar, which displays the gradient that will be applied to the canvas. At the bottom left there's more gradients to choose from. Double-click any gradient to copy it to the color bar.

This group of gradients is called a gradient set. To access other gradient sets, click the name of the current gradient set. This will open a dropdown menu with any gradient sets that were pre-installed, that you created yourself or that you've previously downloaded.

For the following example, we've selected the "Sunset (purple)" gradient from the pre-installed "Sky" gradient set.

If you simply hit OK without changing any further settings, it will have the following effect on the image:

On the left you see the unedited version; the right side shows the same image but with "Sunset (purple)" applied to it.

The effect will be different if you change the correction layer's blend mode or opacity, which we'll explain further in later sections.

Basically, the gradient map correction layer reads the grayscale value (that is, how dark or light the color is) of each pixel in the image. Then each pixel will be assigned a new color in accordance to the gradient: Pure white areas will change to the color to the very right of the gradient, whereas pure black will become the color to the very left. A mid-range color will change to a color along the middle of the gradient, and so forth.

Most gradients you will come across range from a dark color on the left side to a light color on the right. But that's in no way all that is possible for gradient maps. For example, gradients don't necessarily need to have any smooth transitions. They don't need to transition from dark to light, and can have as few or many colors as you wish.

Basics of editing and creating gradient maps

Underneath the color bar are several, small arrows. These nodes each define a specific color. Every other color in the gradient is created by mixing these colors.

You can move these nodes to different positions by dragging them, or enter a different number in the "Position" box to the bottom right. To create a new node, click any empty spot on the gradient. Clicking the garbage can icon to the bottom right will delete the currently selected node.

To assign a different color to a node, click the colored rectangle under "Specified color". This will open a color selector. (You can also select "Main drawing color" or "Sub drawing color" instead; as the names imply this will change the color to whatever the currently selected main or sub color is. This is useful for creating gradients for tools, but we won't go into more depth regarding that since that isn't the topic of this tutorial.)

 

IMPORTANT: Any changes you make to the color bar are NOT automatically saved to the gradient set. To save a gradient to the set, you need to use the buttons below the gradient set.

1. The first button replaces the currently highlighted gradient with the gradient in the color bar. To highlight a different gradient, click it once (twice will overwrite the color bar).

2. The second button does the same as double-clicking the highlighted gradient; it replaces the gradient in the color bar.

3. The third button creates a copy of the highlighted gradient in the gradient set.

4. The fourth button will save the gradient in the color bar as a new gradient.

5. And lastly, the garbage can icon deletes the highlighted gradient from the set.

Now, if you've accidentally overwritten or deleted a gradient you didn't mean to, fear not! If you click "Cancel" instead of "OK", all changes made will be reversed. But that includes ALL changes you've made since you opened the gradient map window, so keep that in mind.

 

The last area of the interface we haven't mentioned yet is the mixing rate curve.

The mixing rate curve of each node determines how its color mixes with the color of the next node to the right. Hence, the rightmost können node does not have a mixing rate curve. Since the mixing rate curves determine how all colors between nodes are mixed, they're one of the most important factors in determining a gradient's look.

The x-axis describes the position, ranging from the position of the left node to the position of the right node. The y-axis on the other hand determines the ratio at which the right color and left color are mixed at a given position.

 

The image below shows the default mixing rate curve (on the right, black node). When the mixing rate curve checkbox is not ticked, it behaves the same as the default curve shown above.

This graph isn't perfectly linear; that means the gradient between the two nodes isn't perfectly smooth. To create a linear gradation, drag the two middle control points away from the graph to delete them.

 

A curve like shown below will result in a direct transition from one color to the next without any color mixing.

 

With black on one end and white on the other, creating an S-curve similar to the default curve results in more very dark grays and very light grays, and less grays in the mid-tone range.

 

A reverse S-curve on the other hand creates more mid-tone grays, and less grays that are very dark or very light.

 

You could also go back and forth between the left and right color several times.

 

You can not only edit the gradients in a set, you can also create entirely new gradient sets. Click the wrench icon next to the gradient set name. There you will not only find options to create a gradient set; you can also change the name of a set, or of a single gradient.

Possible uses for gradient maps

Of course you aren't limited to only the uses listed below. There's endless possibilities on how to utilize gradient maps in your work! These examples are some of the most common and well-known uses, as well as methods I personally use a lot.

1. Colorizing grayscale artwork

You can simply use a gradient map as shown before at 100% opacity Normal to add color to sketches or monochrome artworks. This can make a simple doodle much more interesting before posting on social media, without having to actually color it.

But you can also take it a step further and add local colors on top. The local colors need to be on an Overlay layer or in an Overlay folder. To do this, I recommend changing your paper color to a mid-tone gray, because colors on an Overlay layer won't show up on pure white.

In the image below, there's a purple Overlay applied to both the left and right version. As you can see, the white paper areas of the left version remained fully white.

 

After painting some local colors on top, this is what the same drawing from before looks like:

In the version above I used a simple, warm-toned sepia gradient. But since correction layers are non-destructive, I can still go back and change the gradient. With just two clicks the artwork can get an entirely different atmosphere.

2. Colorizing lineart with opacity

If you like to work with varying opacity in your lineart, gradient maps are a simple yet effective tool to make your lines seem a lot less dull without having to manually color them.

First, put your lineart layer(s) into a folder. Underneath the lines, add another layer and completely fill it with pure white. On top of the lineart, create a gradient map correction layer with the gradient of your choice.

The gradient should have pure white at its right end. If that is not the case, the gradient map will affect not only the lineart, but every color underneath. (Which you could use to your advantage if that's what you're going for, but in this case we want the color layers underneath the lineart to be unaffected.)

The lineart should look something like this so far:

 

And the final step: Change the lineart folder's blend mode to either Multiply or Linear Burn. With both of these blending modes white areas become transparent, so the colors underneath will be visible again.

 

The image below shows the before vs. after. It's a more subtle effect than the previous method, but it creates a nice finishing touch.

 

One thing you need to keep in mind with this method is that if your flat colors aren't clean enough and the lineart is fairly light, the flat colors' edges become visible. As long as your lineart is fairly dark overall it shouldn't be an issue though.

3. Adjusting contrast with Overlay

This is another quick and simple trick to add a finishing touch to a colored artwork. Gradient maps can not only increase or decrease the contrast, they'll also harmonize the color scheme.

Add a gradient map layer like you usually would. To increase contrast, the gradient should transition from dark on the left to light on the right side. A gradient transitioning from light to dark on the other hand will decrease the contrast of the image.

 

You can flip the direction of a gradient map with the button on the right side of the gradient.

 

 

The gradient map correction layer should be above all other layers. Next, you need to set the correction layer's blend mode to Overlay and decrease the opacity if necessary.

In the this case, I used a dark to light gradient map (increasing contrast). The left side shows the gradient map Overlay at 100%, whereas on the right side the opacity is lowered to 50%.

 

4. Turning images to grayscale

Using a gradient map correction layer is the easiest way to accurately turn an image to grayscale. And "accurately" is the important word here, because technically it's easier to add a Hue/Saturation/Lightness layer and turn the Saturation to 0. I used to do the latter to check the values of my artwork, which is just about the worst way to go about it. Don't make the same mistakes I made.

I won't bother you with all the details as to why that is, but as you can see for yourself, the results vary drastically.

The version with 0% saturation looks way different than the other two. The yellow turns out a lot darker than it should, and the blue is too light.

 

To create a grayscale gradient map like used in the example, you can't just add black on one end and white on the other. The mixing rate curve of the black node needs to be linear. If you leave the mixing rate curve at its default, this will slightly increase the contrast of the image.

How to download gradient maps

If you want to have more gradient maps available without having to create your own, you can download gradient maps from Clip Studio Assets.

(A lot of the gradients used thorughout this tutorial are available to download for free on Assets; just search my username "toffl" or visit my profile)

First, like any other brush or material, you'll need to go to Assets, find a gradient set that you like and click the download button on the top right. Next, create a gradient map layer, click the wrench icon next to the gradient set's name, and click "Import material set". This will open a new window with any gradient sets you have downloaded. Selecting one and clicking OK will add it to your list of gradient sets.

(A lot of the gradients used in this tutorial are available to download for free on Assets; just search my username "toffl" or visit my profile)

Process walkthrough: Creating a true to value gradient map

In my work, I almost exclusively use "true to value" gradients. (I made that term up myself, I don't know if there's some other more common term.) Now, what exactly does that mean?

As we explained in the beginning, a gradient map assigns a new color to every color in an image according to its value. A true to value gradient map makes sure that the value of the new color matches the value of the underlying color. In other words, the new color may have a different hue or saturation than the previous color, but the value remains the same.

In other words, you don't need to worry that the gradient will change the values you've already picked.

 

Next, I'll walk you through the process of how I go about creating those gradients.

Step 1: Place pure black and pure white nodes at the end of the gradient.

Step 2: Add whatever colors you want the gradient to consist of. That can be as many or few colors as you like, but keep in mind that the more colors you use, the longer you'll need to finish your gradient.

In this case I added 4 nodes in dark green, indigo, lavender and yellow.

The position value of each color node should match the HLS Lightness value of the color (for now, at least). That way, each color will be at least approximately at the right position to be considered true to value.

So for example, if the yellow's HLS Lightness is 90, move it to position 90, and repeat that for every node.

Step 3: Set the mixing rate curve of every node to linear. To do that, check the"mixing rate curve" box and drag the two middle control points away from the graph to delete them.

Step 4: The last step is adjusting the values. To do this, you first need to set up your canvas as follows:

First, create a layer with a perfectly smooth, black to white gradient. The gradient map you want to edit should be above that. And lastly, at the very top has to be another gradient map layer with a grayscale gradient map.

When switching the gradient map we've been working on on and off, you'll probably notice that the result changes slightly.

The goal now is to change the new gradient map in such a way that the before and after look as similar as possible. You can do that by either changing the HLS lightness of the colors or moving them to a different position. Then, you'll need to check the values again by turning your gradient map on and off. You'll probably need to repeat this process several times before you're satisfied with the results.

Typically, blues and purples need to be moved closer to the left (dark) side, whereas yellows and oranges have to be pushed towards the right (light) side.

(You might also notice some artifacts in the gradient when both the new gradient map and the grayscale gradient map are turned on that you can't get rid of. I have no idea why that happens sometimes so I've elected to ignore it.)

Conclusion and Social Media

And that's already the end of our brief digression into the world of gradient maps.

We hope this tutorial was helpful in some way or another. Since we only covered some basic methods for applying gradient maps, there's many more possibilities for you to explore!

As mentioned in the beginning this tutorial was created by two artists. Esra edited and animated the video while I (Toffl) wrote the tutorial and recorded the voiceover. All drawings, animations and videos used in this tutorial were created by one of us, and all gradients used were pre-installed in Clip Studio Paint or created by me.

Follow us on instagram, twitter or artstation to see more of our art and other content:

 

Esra: esra_arts (twitter, instagram)

(clip studio profile: https://profile.clip-studio.com/en-us/profile/362yzkvzw-o8)

 

Toffl: ktoffl (instagram, artstation)