How to Boost Colours in Affinity Photo

Digital cameras have come on in leaps and bounds over recent years. But sometimes you still just want to boost colours to give images that POP of life.

There are various ways to do it in Serif’s Affinity Photo. Adjustment layers make it particularly easy.

But I want to get you out of your comfort zone! I’m going to show you how to boost colours in Affinity Photo using the Lab colour mode. You’ll use layers, colour formats, and layer masks to really make your images sing.

So let’s crack on!

Preparing the Image

For this tutorial, I’m using this image. It’s my own photo from my 2017 trip to Venice, looking up at the Bridge of Sighs. Or you can use your own and apply the same principles!

So open up your image in Affinity Photo. Go to Document in the top menu bar, scroll down to Colour Format, and across to Lab.

Now you’ve entered a new colour mode. Neither RGB nor CMYK can perfectly replicate the colour spectrum that humans can see. Lab colour was introduced as a way to simulate this.

But you can’t really render it on a screen or print it so it has limited value. Still, for our purposes, it offers a cool way to boost colours.

Moving On To Boost Colours

Now we’re going to actually boost colours. Click on the Adjustment Layer icon (the circle divided into black and white) at the bottom of the layer panel. Choose Curves from the menu.

Under the graph, it will say ‘Master’ on the central dropdown menu. That’s because images in Lab color mode are split into three channels. L, a and b. Hence the name. We want to make changes to a and b. So change the channel to ‘AOpponent’ in the dropdown.

Now you want to click on that central diagonal line and drag it to match the screenshot above. Those boxes dividing the panel into quarters are really useful.

The first anchor you add should be along the bottom axis and one quarter box in from the left. The second is along the top axis, and one quarter box in from the right.

In the Channel dropdown, select channel ‘b’. Repeat this process.

When you’ve finished altering the curves, the image should look something like this.

You can just leave it there if you want. Be warned; if you use this technique on people, their skin tone will end up really unflattering. So we’re going to use a layer mask to reveal part of the original image below. On a portrait, you’d use the layer mask on the skin.

Layer Masks in Affinity Photo

Because Affinity Photo lets you work on adjustment layers, you can apply your layer mask direct to the adjustment layer. So with the adjustment layer selected in the layer panel, simply click on the layer mask icon. It’s the one that looks like a piece of cardboard with a hole in it.

Using a paintbrush set to black, paint over the parts of the adjustment layer that you want to hide. They’ll reveal the colour of the layer below. In this example, I’ve removed some of the excess colour on the brickwork to the left of the image.

When using Layer masks, painting with black hides the layer to reveal what’s below. Painting with white will bring the layer you’re painting on back into view. If you were doing this on a face, you’d bring back the natural skin tone.

To get a soft appearance, use a soft-edged brush. Use the hardness slider in the top menu bar to remove the harsh edges of the brush.

You can add other adjustment layers if you feel they’re necessary. Or you can flatten the image and return to RGB using the Colour Format menu. You’ll need to do that if you want to use the file online since computer screens display in RGB.

And here’s your final piece!

Give it a go! And share your results in the comments below.