Show one colour in Black and White picture

[mapline]

My son and daughter have a Fuji X30 (great camera) which has a filter to show one colour (eg Reds) while others are black & white.

How can I create the effect in Affinity Photo. I can make a black and white layer but with another layer how can I take out the other colours and just leave the reds?

Appreciate help please.

 

[mapline]

Solved it.!

 

1 Make Black & White layer from background

2 Select colour from background reds, greens, or blues and make a new layer with that colour.

 

Job done!

 

If I want more selection I can use a mask.

[CLegair]

Solved it.!

 

1 Make Black & White layer from background

2 Select colour from background reds, greens, or blues and make a new layer with that colour.

 

Job done!

 

If I want more selection I can use a mask.

How do I create a layer using only that colour?

[Madame]

I'm not sure what Mapline meant.

But here's how I would do it.

You have your background layer. (The colour picture)

Add a black and white adjustment layer. (This is a mask)

With a brush and black colour,  just paint over the object you want to be coloured.

[Unlikely Moniker]

Bit late to this topic, I know, but here's how I get the effect the OP is asking about using Affinity Photo desktop:

1. Add a Black and White adjustment layer over the image.
2. In the adjustment layer's properties options box, set the Blend Mode to Lighten
3. Drag the layer property colour slider for your chosen colour, e.g. red, to the right (negative value) to bring out that colour leaving the rest of the image monotone

Try experimenting with the Lighter Colour blend mode as well; it might give a slightly subtler effect.