Adobe Photoshop - “path” coordinates and “path stroke” behavior

Question

I have some things I need to verify in using Adobe Photoshop. I am designing a "precise" dimension related image. It was an archimedian spiral. base on a tutorial I found on YouTube. I have to be familiar with 2 things, the path and the stroke.

Please bear with me if the following numbers is correct:

Suppose I create a canvass with at least 10 pixel width,

then I create a path using ellipse tool with 1:1 from center with with 7px.

1. Am I right to assume that this is what happens, the path transverse the x-axis at 7 px mark?

Then I path stroke the path I just created with a brush configured to 2px.

2. Am I right to assume that from 7px, 5px to 9px are all filled? Like this?

Are my assumptions and images (2) and (3) correct?

Can somebody please tell me if I'm right?

Answer 1

(Did not watch the video)

Stroked paths always place the stroke on the center of the path by default. Although with vector shapes in Photoshop, it is possible to change that stroke alignment via the stroke options. But I'll assume everything is set to the defaults.

The measurement for the stroke is not added to both sides of the path. It's a cumulative figure. A 2px stroke means 1px inside and 1px outside. Your image (3) would require a 4px stroke -- the total sum of pixels to be covered.

I can't tell where you are getting 7px from in your image. If I extrapolate the rest of the ellipse (red line below), the measurement scale seems to have no logical basis for its placement.

In this case, the ellipse based on your posted screenshot is 226px in width. So a 2px stroke would increase the width to 228px - adding 1px to the left and right sides. As well as reducing the diameter to 224px - subtracting 1px from the inner dimensions.