Lasso tool residue when digital painting

[Sami2019]

Hello,

I have the following issue with the lasso tool.

Whenever I paint whithin a lasso tool selection it will paint slightly outside the edges of the selection. This always happens with the first color I use and even if I try to erase the whole thing this residue line will remain.

I have not been able to find a solution online, maybe because I´m not wording my problem properly so I´m using the images below. 

If any of you know how to fix this it would be great.

Thank you very much in advance!

[Sami2019]

Sorry for the typo!!!! (ignore "but the first color")

[c.pfaffenbichler]

Please meaningful screenshots including the pertinent Panels (Toolbox, Options, …). 

What were the Anti-alias and Feather settings? 

The »edge pixels’« semi-selectedness seems to confuse many people. 

Maybe you would be better off painting on Layers with Layer Masks to maintain stronger editability. 

[Sami2019]

Hello C_pfaffenbichler,

Thank you so much for your quick reply!

I attach a screenshot of my whole screen. 

I didnt know about anti-aliasing neither feather settings, so I never played around with those settings... I see now that on that anti-alias is ticked on and feather is 0.

[c.pfaffenbichler]

Anti-aliasing will cause semi-selected pixels (except on perfectly horizontal and vertical, pixel-aligned Edges). 

So say you start with solor 1.

Then you paint in a Selection with color 2 and it will be laid down »partially« on those »edge pixels«.

And if you then paint with color 3 that will also be laid down non-opaquiley on those edges. 

So the resulting color for those pixels would not be a mixture of color 1 and color 3, but of color 1, color 2 and color 3. 

[c.pfaffenbichler]

I am not sure if this is actually your problem but a simple illustration of the issue of »Selection edges« would be this: 

• start with  a white background 

• make a feathered Selection 

• fill it with black 

• fill it with white 

Some people would expect the result to be the same white area they started with. 

But that is simply not a reasonable expectation if the Selection was created with Feathering or even Anti-aliasing (except in the case of a pixel aligned rectangular Selection for example). 

[Sami2019]

So... I've tried to do a little test with your suggestions and now I'm way more confused. 

Ive done three circles some with anti alias ticked on some turned off and with different feather percentages and paint now goes way over the edges....... I'm really confused. 

Also, for some strange reason now is painting as if I had lower opacity selected, when I was using a hard edged brush with 100% opacity.