Excellent Guide to Masking in Affinity Photo

[Mark Oehlschlager]

Affinity Photo's approach to masking is so very different from the methods we are all familiar with in Adobe Photoshop. It's been a source of some frustration for me.

Here is a very helpful tutorial that illustrates three different masking methods in Affinity Photo.

 

 

[Lisbon]

This is brilliant.
Using layers as masks opens up a new set of possibilities.
Thanks for sharing.

 

[dmstraker]

A few other videos on masking here: http://changingminds.org/disciplines/photography/affinity_photo/categories/ap_masking.htm

[NotMyFault]

On 6/17/2021 at 7:16 AM, Mark Oehlschlager said:

Here is a very helpful tutorial that illustrates three different masking methods in Affinity Photo.

 

Excellent tutorial.

There is one slightly incorrect information: when you use a pixel layer nested as mask, you state „it does not work as mask“. This is halfway true and false: The alpha channel of this nested layer is actually used as mask, but the color channels are basically ignored. Try it with a pixel layer with alpha below 1 in some areas, e.g. by using the erase brush with 50% opacity.

[NotMyFault]

Another comment regarding usage of blend mode difference to compare 2 layers and spot differences.

This gives wrong results when the alpha channel is not fully white for all pixels. Try yourself with a copy of a layer not fully opaque, e.g. using a gradient from 0 to 1 on alpha.

Never the less, you can compare such layers, but you need to compare in 2 phases:

1. compare rgb channels, after setting alpha to 1 by channel mixer or PT filter
2. compare alpha channel, after setting RGB=A and A=1

 

[nrx]

If I'm using a shape (circle, pen tool etc.) as a mask, why can't the mask be inverted or its color value changed? It's either on or off, you can't change the fill color to 50% grey for example. You can't invert it. Doesn't matter what color the fill on the shape is, it always creates the same mask.

White fill.
Black fill.
Both create the same mask.

(I don't want to rasterize the shape...I want to keep the shape as a way of being able to manipulate the mask)

 

[MEB]

Hi @nrx,
Vector masks use opacity (not Luminance) to set the transparency. So in your case change the Opacity (colour opacity) on the bottom of the Colour panel to 50%.

[nrx]

8 minutes ago, MEB said:

Hi @nrx,
Vector masks use opacity (not Luminance) to set the transparency. So in your case change the Opacity (colour opacity) on the bottom of the Colour panel to 50%.

That helps, but how to invert the vector mask layer? In the example below I want to use the mask to create  a round hole in the green layer, but the mask isn't working like that and there's no way to invert it (presumably because its using opacity rather than 0-1 white black.)

 

[NotMyFault]

There is currently no way to inverse a vector mask directly (based on unsolved issues).

Never the less, if you follow the process described in the tutorial, it will work perfectly (using groups, blend ranges and blend mode erase).

As this thread is about the tutorial, i would suggest that you create a new separate topic under „questions“ to keep everything organized.  

 

[MEB]

Hi @nrx,
There's no way (feature) to invert a vector mask. But there's ways to do what you want:
1. create a rectangle the size of the document then subtract the circle from it (press alt if you want to create a compound so you can edit the circle independently from the rectangle) then nest it to the Fill layer (drag it over the Fill's layer thumbnail to use it as a vector mask).
2. Drag the ellipse over the fill layer to clip it (not over its thumbnail but over the layer itself) and set the Blend mode of the ellipse to Erase. Note this will be rasterised on export (Erase blend mode).

[telemax]

5 hours ago, nrx said:

I don't want to rasterize the shape...I want to keep the shape as a way of being able to manipulate the mask

This is a solution for creating non-destructible masks:

 

[telemax]

16 hours ago, MEB said:

There's no way (feature) to invert a vector mask.

The Affinity community has created a mask that gives this opportunity! You can use it to create a complex design.

Opportunities

• Nondestructive editing and moving
• Multiple individual mask parts
• Vector and raster
• Color and greyscale
• Applying adjustments