Unmultiply for Affinity Photo -Remove black/Remove white

Macros for Affinity Photo to remove the black/white background, known as "Unmultiply".
You can do almost the same thing by the "Erase White Paper" filter in Affinity Photo.
With these macros, There is No color change, No black/white fringe, No detail missing.

Remove black
Remove black -masked
Remove black with a fill layer
Remove white
Remove white -masked
Remove white with a fill layer
Unmultiply alpha
Unmultiply alpha -preserved

– Known as unmultiply
–– Get a masked layer instead of alpha-premultiplied one
–– On a black layer, the appearance will not change
– Inverted version of the Remove black
–– Get a masked layer instead of alpha-premultiplied one
–– On a white layer, the appearance will not change
– Unmultiply the premultiplied alpha
–– Pixels which are completely transparent will remain at alpha 0

1 Download the macro file from the link at the end of this page.

2 Import the file into the library panel. See Affinity official documents or refer to other helpful sites.

3 Select the layer and click on the macro you want to run.

*Try the macro "with a fill layer" in the list and switch the visibility of the fill layer that will be created. And you will see what these macros are all about.

*If you want the black/white areas to be completely transparent, make sure that the color of the area is completely black/white before running the macro. You can use the levels adjustment or something.

levels adjustment

Unmultiply

Remove black Remove white