Affinity Photo : How To Save Selections To Channels Tutorial
Marquee tools / Freehand
How to save Affinity Photo selections to channels, open an image and then go to the tools panel and use one of the marquee tools / freehand etc such as rectangular marquee etc or use the select menu and use one of those commands to create something to be saved
Once you have created your marching ants around a part of the image, perhaps add a feather etc then go to the select menu and save selection as spare channel. You can set the feather to 20 and 30 or higher and the result will be a more blurry mix of any applied effect and the edge and rest of the image.
Go to the view menu and studio and display the channels panel and in that you will see you now have a new spare channel. You can move your marching ants or create a new one and you can then repeat the command to create a new one. You can always rename it as well as delete by going to the entry in the panel and right click and use rename or delete or duplicate.
Load to pixels
you can also do some more things such as load to pixels which restores your marching ants in the location previously set.
Add / Subtract / Red etc
You can also add to existing one as well as subtract from the current as well as load to the red, green etc.
Afphoto native format
It is a useful way to restore all these for future use as they are stored with any saved document to the afphoto format