Why removed background is not 100% transparent?

[Magdalenad]

Hi,

I wanted to cut out background (it was white), I used only Selection Brush Tool. After saving it as png it turned out there are some "stains" and that background is not 100% transparent. Any ideas what did I do wrong?

Cutting out in Affinity:
https://ibb.co/t8MCvdz

After moving PNG on pink background:
https://ibb.co/RTtVyPC

Thanks in advance for your help.

[DWright]

Hi @Magdalenad,

Welcome to the forum

You can also remove a white background by using the Erase White Paper filter from the Filters>Colours menu, if the image does not have a completely white background such as noise on a jpeg this can leave ghost marks on the transparent background

[GarryP]

Unfortunately I don’t seem to be able to check your image with the removed background as the image I can download from your link has no transparent background (it contains the chequerboard). Maybe that’s something to do with the imgbb website.
However, I can see some areas where the background doesn’t look to have been removed completely. See my attached image where there is a marked difference in ‘tone’ to the chequerboard.

[PaulEC]

1 hour ago, DWright said:

Hi @Magdalenad,

Welcome to the forum

You can also remove a white background by using the Erase White Paper filter from the Filters>Colours menu, if the image does not have a completely white background such as noise on a jpeg this can leave ghost marks on the transparent background

But be aware that this will also leave some areas of a photo semi-transparent, so that if you put it on a coloured background, some of the colour will show through the image.

[stevenh]

Often i will make a temporary background layer with about a 15% black fill – I use to see if there are any ghost pixels after removing the image background.

For me it's easier to see than on the checkerboard

[Magdalenad]

Thank you for all your replies! It turned out I used "Select by Sampled Colour" or sth like that ant that's why my selection was imperfect (what I did not notice).