Greetings! I believe I have inadvertently activated an anti aliasing feature on GIMP 2.8.At any rate, I'm suddenly getting several pixels per one mouse click or drag, in different shades and patterns.Is there a way to stop this from happening? I don't have a lot of experience with GIMP, so I don't want to go trying things without advice.Thanks!

That is how Gimp (and all bitmap editors) work. It will depend on the brush, brush size and foreground colour that you have selected.

Try using the Pencil tool with a small brush size. The Pencil is similar to the Paintbrush. The difference is that the Pencil does not have anti-aliasing, whereas the Paintbrush does.

Thanks for your reply. I should have mention that, though inexperienced, I've been using Gimp quite a lot over a moderate amount of time, and this is something that just changed. I've been using airbrush, brush, and pencil, and ask have

Oops, hit submit by accident. Anyway I've always been able to create a single pixel before this, without anti aliasing appearing.

The Paintbrush has a soft edge (ie it has anti-aliasing pixels). The amount of softness depends on the hardness of the brush selected. The Pencil has a hard edge (ie no anti-aliasing pixels). The airbrush has a very soft edge.

To hit a single pixel, use the Pencil, pixel brush, and brush size 1.

Thank you again. I understand what you're saying about the pencil, but I'm frustrated by this other change. In the past, with airbrush, I could make a single mouse click, no matter what size or hardness setting, and only one pixel would appear.

If I held down the mouse, the pixel would get darker, but no other pixels would appear. This leads me to believe that there is a way to remove the function for a given project.

Maybe you had an active selection. Then the paint tools would only affect the pixels within the selection.

Hmm, not sure what you mean by that. Basically, after opening GIMP, I've dragged a pdf or png file into the work window that becomes available. Then I'm able to use airbrush in the manner I've described. I appreciate your help and time, welcome more suggestions, but done feel obliged. :-)

If there's any easy way for me to learn about the active selection you mentioned, and how to duplicate it, I'm all ears. I'd love to get this figured out. Thanks again.

I could also add that I was poking around the anti aliasing function, because I was considering using it on a particular section of my graphic. So it would seem I triggered something larger.

I noticed there was a "reset" option for filters, so maybe that's the key? I don't want to mess up anything else, though, ha-ha.

Yes, but not at the moment. I actually have Gimp on another computer which had not been affected by this isdue, so will try to put up some examples of that as well. Thanks.

First, thanks for the welcome! Second, so, you all are going to think I'm crazy, but I managed to load a file with the anti aliasing in effect, onto my computer with the version of GIMP that *wasn't* having the issue, and bingo, it triggered the anti aliasing on that computer as well. So I have no examples of the "before" to share. I'm trying to post the set-up and "after" results, but perhaps it's a moot point now. Anyway, here's hoping they display when I click submit. This all sounds kind of lame now, so sorry about that, lol.

Hey, it worked! Anyway, none of the anti aliasing you see on the "after" image appeared before I had this issue, when making the same shapes. Okay, time to step away from the computer for a while, heh.

Gimp works on the active layer; and within the active selection. (If there is no active selection Gimp will work on the entire layer.)

The image shows the Selection Tools and the Select Menu. Have a look at (Select > None). If it is greyed out there is no active selection. If (Select > None) is available then you do have a selection.

Here is a link to the docs for the selection tools:
https://docs.gimp.org/en/gimp-tools-selection.html

Thanks once more! I'll take a look.

Here is what my tool selection looks like. Also, I should have mentioned that another change I mention was that my cursor size is suddenly much smaller when I open GIMP. The attachment above size above is "1", but at my Gimp screen is has been enlarged by 3 clicks, and the pixel size is usually much bigger (ignore the cord; it appeared when I used my screenshot function). Does this offer any clues? Thanks.