Emulating Blend mode AND, OR, XOR with Affinity Photo and Apply Image Filter

NotMyFault · January 5

Blend mode AND, OR, XOR with Affinity Photo

Out of the box, you won’t find the blend modes AND, OR, XOR in Affinity Photo V1 or V2. Luckily there is the option to use the “Apply Image” filter which allows to create self-defined blend formulas. As the formulas are quite complex and long, the best way is copy the formulas into your favourite text editor, and copy/paste them into the filter one-by-one.

The steps are relatively simple, but you need to follow an exact sequence of several steps to get it right.

Preparation steps

Have 2 pixel layers present in file, ideally of identical size (pixel x and y). I name the layers “destination” and “source” within this tutorial. The destination layer will be modified and show the result, the source layer stays unchanged.
If you want to use vector layers, make a copy and rasterise them.
Have text editor with formulas open parallel to Photo.
There is one formula for every colour channel. The formulas are made specifically for RGB colour model. They can be adapted for any other colour model (GREY, CMYK, LAB) by search and replacing the variable names of colour channels. I leave this task as an exercise for the reader.

Steps to blend 2 layers with your chosen formula (AND, OR, XOR)

Select destination layer
Choose Filter-> Apply Image
Drag the source layer (from layer stack) into source area of the filter UI. The canvas will show the selected source area, as the default formula uses 100% of the colours from the source layer. You will change the formulas in the next step
Activate box “Equations”
Copy / paste the 3 formulas for the individual colour channels DR / DG / DB
Click apply
The destination layer shows the result

Limitations

Unfortunately, this filter is “destructive”, meaning it will be applied to a pixel layer and stores the result as pixel layer. As of Photo 2 V 2.0.3, there is no way to have this as non-destructive live filter.
You can re-apply the filter, using the same formulas and source image, to other destination layers.
If you want to use it on different source image data, you need to apply the filter again from scratch.
Even worth, there is not easy way like preset to save the formulas inside Affinity.
If you use the macro recorder, you will be bound to the source layer used when recording the macro.
You can store the formulas as text layers within Affinity Photo, and optionally save / export them as Assets. The only advantage is having everything consolidated “inside” Photo, the workflows gets more complicated in case you try to use the text frames as source for copy/paste.

Formula for AND

R:

(((((((irem(idiv(SR*255,128),2)*irem(idiv(DR*255,128),2)×2+irem(idiv(SR*255,64),2)*irem(idiv(DR*255,64),2))×2+irem(idiv(SR*255,32),2)*irem(idiv(DR*255,32),2))×2+irem(idiv(SR*255,16),2)*irem(idiv(DR*255,16),2))×2+irem(idiv(SR*255,8),2)*irem(idiv(DR*255,8),2))×2+irem(idiv(SR*255,4),2)*irem(idiv(DR*255,4),2))×2+irem(idiv(SR*255,2),2)*irem(idiv(DR*255,2),2))×2+irem(idiv(SR*255,1),2)*irem(idiv(DR*255,1),2))÷255

G:

(((((((irem(idiv(SG*255,128),2)*irem(idiv(DG*255,128),2)×2+irem(idiv(SG*255,64),2)*irem(idiv(DG*255,64),2))×2+irem(idiv(SG*255,32),2)*irem(idiv(DG*255,32),2))×2+irem(idiv(SG*255,16),2)*irem(idiv(DG*255,16),2))×2+irem(idiv(SG*255,8),2)*irem(idiv(DG*255,8),2))×2+irem(idiv(SG*255,4),2)*irem(idiv(DG*255,4),2))×2+irem(idiv(SG*255,2),2)*irem(idiv(DG*255,2),2))×2+irem(idiv(SG*255,1),2)*irem(idiv(DG*255,1),2))÷255

B:

(((((((irem(idiv(SG*255,128),2)*irem(idiv(DG*255,128),2)×2+irem(idiv(SG*255,64),2)*irem(idiv(DG*255,64),2))×2+irem(idiv(SG*255,32),2)*irem(idiv(DG*255,32),2))×2+irem(idiv(SG*255,16),2)*irem(idiv(DG*255,16),2))×2+irem(idiv(SG*255,8),2)*irem(idiv(DG*255,8),2))×2+irem(idiv(SG*255,4),2)*irem(idiv(DG*255,4),2))×2+irem(idiv(SG*255,2),2)*irem(idiv(DG*255,2),2))×2+irem(idiv(SG*255,1),2)*irem(idiv(DG*255,1),2))÷255

Formula for XOR

(((((((1-abs(irem(idiv(SR*255,128),2)+irem(idiv(DR*255,128),2)-1)×2+1-abs(irem(idiv(SR*255,64),2)+irem(idiv(DR*255,64),2)-1))×2+1-abs(irem(idiv(SR*255,32),2)+irem(idiv(DR*255,32),2)-1))×2+1-abs(irem(idiv(SR*255,16),2)+irem(idiv(DR*255,16),2)-1))×2+1-abs(irem(idiv(SR*255,8),2)+irem(idiv(DR*255,8),2)-1))×2+1-abs(irem(idiv(SR*255,4),2)+irem(idiv(DR*255,4),2)-1))×2+1-abs(irem(idiv(SR*255,2),2)+irem(idiv(DR*255,2),2)-1))×2+1-abs(irem(idiv(SR*255,1),2)+irem(idiv(DR*255,1),2)-1))÷255

(((((((1-abs(irem(idiv(SG*255,128),2)+irem(idiv(DG*255,128),2)-1)×2+1-abs(irem(idiv(SG*255,64),2)+irem(idiv(DG*255,64),2)-1))×2+1-abs(irem(idiv(SG*255,32),2)+irem(idiv(DG*255,32),2)-1))×2+1-abs(irem(idiv(SG*255,16),2)+irem(idiv(DG*255,16),2)-1))×2+1-abs(irem(idiv(SG*255,8),2)+irem(idiv(DG*255,8),2)-1))×2+1-abs(irem(idiv(SG*255,4),2)+irem(idiv(DG*255,4),2)-1))×2+1-abs(irem(idiv(SG*255,2),2)+irem(idiv(DG*255,2),2)-1))×2+1-abs(irem(idiv(SG*255,1),2)+irem(idiv(DG*255,1),2)-1))÷255

(((((((1-abs(irem(idiv(SB*255,128),2)+irem(idiv(DB*255,128),2)-1)×2+1-abs(irem(idiv(SB*255,64),2)+irem(idiv(DB*255,64),2)-1))×2+1-abs(irem(idiv(SB*255,32),2)+irem(idiv(DB*255,32),2)-1))×2+1-abs(irem(idiv(SB*255,16),2)+irem(idiv(DB*255,16),2)-1))×2+1-abs(irem(idiv(SB*255,8),2)+irem(idiv(DB*255,8),2)-1))×2+1-abs(irem(idiv(SB*255,4),2)+irem(idiv(DB*255,4),2)-1))×2+1-abs(irem(idiv(SB*255,2),2)+irem(idiv(DB*255,2),2)-1))×2+1-abs(irem(idiv(SB*255,1),2)+irem(idiv(DB*255,1),2)-1))÷255

Formula for OR

((((((clamp(irem(idiv(SR*255,128),2)+irem(idiv(DR*255,128),2))×2+clamp(irem(idiv(SR*255,64),2)+irem(idiv(DR*255,64),2)))×2+clamp(irem(idiv(SR*255,32),2)+irem(idiv(DR*255,32),2)))×2+clamp(irem(idiv(SR*255,16),2)+irem(idiv(DR*255,16),2)))×2+clamp(irem(idiv(SR*255,8),2)+irem(idiv(DR*255,8),2)))×2+clamp(irem(idiv(SR*255,4),2)+irem(idiv(DR*255,4),2)))×2+clamp(irem(idiv(SR*255,2),2)+irem(idiv(DR*255,2),2)))×2+clamp(irem(idiv(SR*255,1),2)+irem(idiv(DR*255,1),2)))÷255

(((((((clamp(irem(idiv(SG*255,128),2)+irem(idiv(DG*255,128),2))×2+clamp(irem(idiv(SG*255,64),2)+irem(idiv(DG*255,64),2)))×2+clamp(irem(idiv(SG*255,32),2)+irem(idiv(DG*255,32),2)))×2+clamp(irem(idiv(SG*255,16),2)+irem(idiv(DG*255,16),2)))×2+clamp(irem(idiv(SG*255,8),2)+irem(idiv(DG*255,8),2)))×2+clamp(irem(idiv(SG*255,4),2)+irem(idiv(DG*255,4),2)))×2+clamp(irem(idiv(SG*255,2),2)+irem(idiv(DG*255,2),2)))×2+clamp(irem(idiv(SG*255,1),2)+irem(idiv(DG*255,1),2)))÷255

(((((((clamp(irem(idiv(SB*255,128),2)+irem(idiv(DB*255,128),2))×2+clamp(irem(idiv(SB*255,64),2)+irem(idiv(DB*255,64),2)))×2+clamp(irem(idiv(SB*255,32),2)+irem(idiv(DB*255,32),2)))×2+clamp(irem(idiv(SB*255,16),2)+irem(idiv(DB*255,16),2)))×2+clamp(irem(idiv(SB*255,8),2)+irem(idiv(DB*255,8),2)))×2+clamp(irem(idiv(SB*255,4),2)+irem(idiv(DB*255,4),2)))×2+clamp(irem(idiv(SB*255,2),2)+irem(idiv(DB*255,2),2)))×2+clamp(irem(idiv(SB*255,1),2)+irem(idiv(DB*255,1),2)))÷255

Source layer