Select Modify Expand command inconsistent and deviates randomly

[Stick Figure Art]

Is this just a programming error? Is there a work around so that I can expand my line by the same pixel amount in a consistent way? I use this function many times a day. I see now why I've had some real pain in the rear problems that would have been totally avoided if my line had redrawn correctly.

The image I uploaded is of 2 screenshots that I overlaid. It's a before and after of a 1 pixel expansion using Select>modify>expand. I'm using the latest CC if that makes any difference.   Thanks for your input.

Chris Warren

[c.pfaffenbichler]

Is this just a programming error?

That seems unlikely, the issue is more likely the original Selection.

(Please post a screenshot of the Selection saved as a Channel taken at View > 100%.)

You might be better served working with Paths, though without knowing the complete procedure and aim it’s hard to tell.

[D Fosse · Accepted solution]

This is about partially transparent pixels. That's a partial pixel, not a full one. You have marked in green pixels that are almost fully transparent.

I don't see anything here that looks particularly unexpected for a 1 pixel expansion.

If you've had trouble with selections before, that's probably for other reasons.

[Stick Figure Art]

Thank you. That is exactly what is happening. When using the expand command it doesn't recognize any pixel that is less than 50% opaque.

When I expand my line, most times it's so I can either clean up or shade part of the image; OR, clone or clear a large area of pixels surrounding the image.

I'll have to rewrite my question explaining my end goal and resubmit it. Thank for helping me understand what's happening.