Hi! This tutorial explains how to create iridescent effects, like what you might see on soap bubbles, pearls or oil spills, without having to manually colour it. Instead, we can use gradient maps to quickly generate these beautiful colours from grayscale drawings.

What are gradient maps?

The easiest way to explain what gradient maps are is to demonstrate what it does to a black and white gradient.

 

To add a gradient map go to [Layers] -> [New Adjustment Layer] -> [Gradient Map]

 

Gradient maps work by assigning colours to the layers underneath it based on how light or dark each pixel is.

The colour on the left gets assigned to black pixels, the colour on the right gets assigned to white pixels, and everything in between gets assigned to a corresponding value of grey.

Any amount of nodes can be added in between the two extreme nodes, and all of them can be rearranged.

Downloading and importing the Gradient Map material

To download the gradient set used in this tutorial for free, follow this link, or alternatively search "Iridescent gradient map" on Clip Studio's asset store.

To import the downloaded gradient set for use, go into the settings for a gradient map layer by double clicking on it. Then click on the wrench icon, then "Add gradient set".

The material should appear under "Downloaded materials"

Painting colour patterns

To make an iridescent soap bubble, start with a white circle and erase the centre with a soft round brush.

Keep the two gradients at the top, as it will help you know which shades of grey will produce which colour.

Create a new layer for the values above the white base, and mask it out with a selection made from the base. (use the wand tool to select outside the base, invert selection, go back to the the new layer and hit the mask icon).

Create a gradient map layer above the value layers select (Clip to layer below) and select the "Iridescence" gradient from the set.

On the values layer start painting with black and white using a soft round brush, preferably with "color mixing" checked in the tool settings. Push and pull the values, switching between black and white or selecting a grey from the gradient above that corresponds to the colour you want to add.

Erase the values with a soft eraser until it looks right, add a highlight layer above the gradient map layer set to "Add" or "Add (Glow)" blending mode (It needs to be above the gradient map layer, otherwise it will be affected by the gradient map)

Play around with the blending modes of the gradient map layer. I set it to "Pin Light" because it produced a nice effect.

The "Pearlesence" gradient in the set is configured for pearls, which tend to have narrower bands of colour, and have less bright effects.

Use the same techniques as above on a simple shaded sphere and adjust the opacity and blending layer of the gradient map (I set it to 50% opacity, and "Pin Light")

 

Remember to clip the gradient map layer to the values layer, otherwise it will affect the base and the shading layer.

And that's it!

Experiment with different brushes, blending modes and remember to just have fun!