EDITING - Using the Pen Tool to make selections

Selecting individual parts of an image is a key skill required for creating fine art architecture images. 

Previously, I have shown why I make my selections manually (EDITING - Why I make my own selections in Photoshop). In this post I will explain how I use the Pen tool to make my selections.

Learning the pen tool in Photoshop has been one of the hardest things I have done, but also one of the most worthwhile. Before using the Pen tool I made most of my selections using the Polygonal Lasso tool, but my friend Jon Knight suggested that I would benefit from learning how to use the Pen tool instead.

At its most basic level, the pen tool allows you to create a path in your image, for selections this is a closed path - i.e. one that forms a 2 dimensional shape in your image. One of the immediate benefits is that the path can be edited after it has been drawn - adding, removing or moving points.

Showing a simple straight line made by clicking two points with the pen tool

If you just click to add more points, the pen tool will draw a straight line from the previous point to the current position. Hovering over the first point causes the tool to show a small circle next to the pen pointer to indicate that you are closing the path. Hovering over any line on the path will show a small plus symbol indicating that you are adding an additional point. Hovering over any existing point will show a small minus symbol indicating that you are removing an existing point. If you want to move an existing point, you click on the point whilst holding down the CTRL key - make sure that the point is shown selected and then move it (there is a mode where you move the whole path, so it is important to ensure you have the point properly selected before continuing).

Once you have drawn your path you have a number of options for converting to a selection. I typically just use the Selection… option in the tool specific toolbar.

Once you have a completed shape you can choose the Selection... option in the toolbar

This shows the “Make Selection” dialog where you can adjust feathering etc. Personally I don’t change any of those settings because I tend to want hard selections as they give me the clean lines I like in my images, you may find these settings more useful. If there isn't already a selection, the only available Operation will be New Selection. If there is already a selection you can add to it, remove from it or intersect with it.

The "Make Selection" dialog showing the options for the selection

So far, so simple. The real power (for me at least) of the Pen tool comes in when you move on from straight lines and on to curves. Before using the pen tool, creating a selection involving a curve required me to make lots of small straight lines using the Polygonal Lasso tool, which could lead to jagged edges which always annoyed me. Using the Pen tool I can simply draw a curve and try to get it to fit the curve in the image.

To do this you hold the mouse button down when you add a point and move the mouse, revealing a pair of curve adjustment controls. You can also convert an existing straight line point to a curve point by clicking on it whilst holding down the ALT key. One of the handles controls the curve from this point to the next point, whilst the other controls the curve from this point to the previous one. If you simply click on one of the control points and start moving the mouse it moves both control points together - to separate them, click on one whilst holding down the ALT key and you can then move that point without affecting its partner. As you move the control point you will see the curve drawn and you can then alter its shape by moving the control point. The curve is based on Bézier curves and you can fit to almost any curve using this technique. You sometimes have to add an intermediate point to get the fit you want, but also going back to the controls on the previous point can also help to get a really good fit on the curve.

Normal point converted to curve point - note the two control point handles (white circles)

Dragging the LH control point to the left and up adjusts the curve to fit the image

This article just scratches the surface for the Pen tool, there are lots of other features that it supports that I haven’t needed to investigate yet.

If you are interested to see more of my images, please check out my website.