Background Removal Issues

[scopes78]

I am trying to remove background from a picture of handwritten text and export it to a PNG with transparent background. I open a JPEG image in Affinity Photo. Adjust image to B&W and adjust brightness and contrast. I then go to Select=> Sampled Color and adjust to select everything but the text. I delete selection and I have included a screenshot of what I get. I then export as a PNG. The PNG file has a lighter background on it that I can't seem to get rid of. If I delete the selection, shouldn't it be gone with no trace?

Document=>Transparent Background is checked

I have made sure Matte in PNG export is "nothing"(red line through it).

I have also tried Filters=>colors=>Erase White Paper with a similar end result.

I have attached the original file and a screenshot of the final product in AF Photo. It got an error when I tried to upload the PNG file.

I have spent a lot of time trying to figure out what I am doing wrong.

Any help would be greatly appreciated!

Thank you in advance

 

[firstdefence]

Easiest way would be to split the image in half and apply the threshold filter to each half.

1. Select the top part “Text Test Pen" using the rectangle marquee tool 
   
2. Now Cut (Command + X) and paste Command +V the selection
   You should now have something like this...
   
3.  Select the top Layer and apply a Threshold filter using 59% and hit Merge.
   
4. Do the same with the bottom layer but use 50% and hit merge
5. Now select both layers, right-click  and merge visible
6. Delete the old layers used to merge visible
7. Apply the Erase White Paper filter.
    

[scopes78]

Wow! Thank you very much! It worked perfectly! I'm very new to this software and I don't know how many hours I spent trying to get this to work. This method is so quick and simple.

Again, thank you very much!