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Edit > Stroke Selection, Line width odd/even and antialiasing

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Edit > Stroke Selection, Line width odd/even and antialiasing DJ 16 Jun 05:50
  Edit > Stroke Selection, Line width odd/even and antialiasing Sven Neumann 17 Jun 10:25
   Edit > Stroke Selection, Line width odd/even and antialiasing Simon Budig 17 Jun 11:23
DJ
2009-06-16 05:50:12 UTC (over 15 years ago)

Edit > Stroke Selection, Line width odd/even and antialiasing

Hi Gimp-user,

Just wondering why, odd pixel widths look different than even pixel widths when using Edit > Stroke Selection?

The odd pixel lines looked aliased, while the even pixel lines don't (only their corners).

When drawing icons and shapes, do you make a conscious decision to stroke the line with an odd or even line width?

I tested this by drawing a selection on a layer and stroking it with line width 1, then adding a layer, moving the selection to the right, and stroking it with line width 2. I repeated that 4 times increasing the line width each time.

Thank you.

Sven Neumann
2009-06-17 10:25:58 UTC (over 15 years ago)

Edit > Stroke Selection, Line width odd/even and antialiasing

Hi,

On Mon, 2009-06-15 at 22:50 -0500, DJ wrote:

Just wondering why, odd pixel widths look different than even pixel widths when using Edit > Stroke Selection?

Just think about it. You are stroking along the pixel borders. An even line width will cover pixels exactly. An odd line width will only cover the outer pixels by 50%.

Sven

Simon Budig
2009-06-17 11:23:40 UTC (over 15 years ago)

Edit > Stroke Selection, Line width odd/even and antialiasing

Sven Neumann (sven@gimp.org) wrote:

On Mon, 2009-06-15 at 22:50 -0500, DJ wrote:

Just wondering why, odd pixel widths look different than even pixel widths when using Edit > Stroke Selection?

Just think about it. You are stroking along the pixel borders. An even line width will cover pixels exactly. An odd line width will only cover the outer pixels by 50%.

Actually at some point someone seems to have done a "fix" that offsets the stroke by 0.5 pixels if the brush has an odd width. At least it feels like this, since stroking a 1 pixel brush with the paintbrush yields a black one-pixel line offset 0.5 pixels against the selection outline.

Argh.

Bye,
Simon