Blend modes determine how layers mix or combine with any visible layers below them. More, accurately, they determine how the colors of layers blend with any other colors underneath them. Blend modes can be used to create striking artistic effects, retouch images, and a whole lot more.
You can choose blend modes in a few different places in Pixelmator Pro. One of the most basic uses is changing the blend mode of an entire layer. By default, layers have the Normal blend mode and 100% Opacity. This means that, if an entirely blue layer is above an entirely red layer of identical shape and size, all you see is the blue layer. If you change the blend mode, the blue object will be combined with the red object according to the blend mode.
You can also change the blend mode of certain tools, like the Color Fill tool, so when you fill an area, the color you fill is blended with the colors of the layer you’re filling.
You can also quickly change the blend mode and layer opacity at the bottom of the Layers sidebar.