Layer transparency issue (Erase Paper)

[rjmron]

I'm using Affinity Photo, and I'm trying to use Erase Paper to make the background of an image solid white. The photo was taken on a white backdrop, and is mostly white - most pixels show up as (245,245,245). I did an Erase Paper, which did a good job of making the background transparent. I then added a layer underneath that was pure white (255,255,255). The odd thing is that it's not working like I'd expect:

When only the photo layer is visible, I see the image with a transparent background

When only the background layer is visible, I see a white background that is all (255,255,255)

When both are visible, I get the original image - the white background is (245,245,245)

I'm new to this app, so I may be missing something simple. Can someone help me out?

[Old Bruce]

1 hour ago, rjmron said:

When only the photo layer is visible, I see the image with a transparent background

The Background may be not completely transparent.

[firstdefence]

I'm not a fan of the erase white paper filter, If you have white in the parts you want to keep it can remove them so you'd have to mask those anyway. If you want to remove the white paper, I would suggest using the pen tool to select the object you want to keep, and make a selection from it. that way you get a decent selection and the background you want.

[rjmron]

It's probably best that I just attach the file here. Thanks in advance to anyone who wouldn't mind spending a minute to help me out! It seems like this method should work, and knowing why it isn't would help me get up to speed in this app.

 

 

 

 

[firstdefence]

To show you how ineffective the erase white paper is, get the eraser brush and set everything 100%, go to the image layer and make sure it's selected, now try erasing an area that looks white.

[v_kyr]

The bottom part of that image (down below the sound mixer) isn't fully transparent, do as firstdefence said and you will afterwards see the difference.

[rjmron]

Got it, thanks everyone!

I thought that if I saw the checkerboard that it was actually transparent, but I see now that it's not entirely. I suppose that it shouldn't be surprising that a fully automated tool doesn't work as expected.

 

[firstdefence]

This shows one of the disadvantages of using erase white paper.

 

[firstdefence]

Had a play with the file: PBC6X_back tweaked.afphoto Saved with history so you can jog back and forth in the history panel. 

 

[R C-R]

16 hours ago, firstdefence said:

This shows one of the disadvantages of using erase white paper.

The Erase White Paper filter is really only of much use for working with line art drawn on whitish paper or similar physical media after scanning it into a file. From what I can tell, it erases every pixel with less than a 50% HSL lightness value, ignoring hue or saturation values, although I am not sure about that.

It works fairly well for line art created with sharp edged drawing tools like technical drafting pens but not for much else.