This function allows you to draw Parallel Gradation. You can also use it to apply even gradation, or create striped patterns, by adjusting the contrast and number.
Prepare an illustration you want to add gradation to.
Open ①the Layer window, and add to the top ②a new layer.
From ①the Tool Selection window, select ②Filter.
Select ①Parallel Gradation.
Drag ①the sliders left and right to adjust the wavelength and angle. Finish by tapping ②✓.
After completing the upper gradation, next we will cover the lower gradation.
Open ①the Layer window, and add ②a new layer.
Launch the Parallel Gradation, and drag ①the sliders and draw the lower gradation. Tap ②✓ to finish.
Once you are finished setting the gradation, go back to ①the Layer window and combine ②the 2 gradation layers.
Once you are done combining, from ①the blend mode, select ②Color Burn.
Drag ③the Opacity slider left and right to adjust the opacity.
The figure on the left is before applying gradation, and the right is after applying gradation. Adding gradation to the whole can change the overall impression.