AffinityMike

Do we have something similar in Affinity Photo...?
 
I have some 3D renders that I created in Cinema 4D. I have an object mask/channel (created in Cinema) to cut it out.
I want to save the render with transparency so they can change the background color easily, but I have a little color fringe in the borders. 
 
With Photoshop I can use the "defringe" or "remove white matte" option from the Matting menu and fix it with one click.
In Affinity Photo i tried using the defringe filter but it's not working, I guess it's not the same definition.
Is there a similar tool we can use in Affinity Photo?
 
Thanks
 

Thanks, UncleMonkey. I also recently came to a simple and functional solution. (This official tutorial led me to that thought:
) 
- use Levels or Curves
- change color space to CMYK (for that adjustment)
- set Black Level to 100% for Cyan, Magenta and especially Yellow (for Levels) or drag down teh end point of Cyan, Magenta and Yelow curve (for Curves)
 
I guess, this might be quite a universal attitude for different and more colourful images...

Thanks, MEB.  I still couldn't get the expanded steps to do what they should.  Invert Adjustment continued to leave me with white text on a black background.  However, this worked for me.
 
1. In the Green Channel, create Luminosity layer
2. Turn Visibility off in the Background layer
3. Adjust Levels till the gray disappears
4. Merge Visible
5. Colors/Erase White Paper

LilleG,
After applying the Invert adjustement, select it and the image, make them the only visible layers, right-click on them in the Layers panel and select Merge Visible from the contextual menu (or go to menu Layer ▹ Merge Visible). Only then you can apply the Erase White Paper filter. Sorry for the trouble. I should have detailed all the steps.

I've used the Green channel to create a Luminosity layer, adjusted its Levels, applied an Invert adjustement, then filter Colors ▹ Erase White Paper.
 
Here is the result (transparent):
 

I feel like a dummy here but I can't make MEB's method work.  Apparently there is a too-obvious-to-mention step that I am leaving out but I wind up with Mad Bar in white on a black background.