• Open Test.png,
  
• Wand-select with a Threshold of 15 (I didn't even make it larger than th edefault)
  
• Edit>Clear
  
• Add red layer below to make any remnants of green more obvious:
  

(10-12-2018, 08:52 AM)rich2005 Wrote: It is not unreasonable to request the image file, even better, the same file exported to png in both Gimp 2.10 and Gimp 2.8 for comparison. There will be differences between the Gimp versions.

However, that last post does raise one question. Why all that anti-aliasing? That is not going to happen because of export to png unless you have some intermediate stage.

My guess is it is the image viewer you are using, which both introduces anti-aliasing and does not handle transparency very well.

As an example, this screenshot. Your image reproduced, 8 pix x 9 pix 8 bit RGB, single layer with transparency. Drawn with the pencil tool for hard edges.



In Gimp 2.10 exported two png images, one with Save colour values from transparent pixels (SCVFTP) on - the default setting and one with it off.

Using 2 different image viewers, both display that tiny image incorrectly.

Viewer 1 handles transparency incorrectly. If SCVFTP is on shows the colour, if off displays transparency as black. But no anti-aliasing which is correct.

Viewer 2 Handles transparency correctly, represents it as a checker pattern, but mangles the image by introducing anti-aliasing. Not normally noticeable on a normal image but very obvious here.

Questions:
What image viewer are you using? Have you tried an alternative?
In Gimp 2.10 have you tried SCVFTP off and if so does it affect the outcome.