Selections

A selection is a fence around part of the picture. While one exists, almost everything you do happens inside it and nothing happens outside it — painting, adjustments, effects, deleting, copying.

The moving dashed outline is how you know one is active.

The outline is drawn at a constant width whatever the zoom, so it stays visible when you are working close in.

The tools

Tool	Key	Use it for
Marquee rect	S	Rectangles — crops, borders, anything with straight sides
Marquee ellipse	S again	Circles and ellipses
Polygon	L	Clicking corner to corner around a straight-edged object
Lasso	L again	Drawing a freehand outline by dragging
Wand	W	Everything touching this point that is a similar colour
By color	Q	Every pixel in the picture of a similar colour, touching or not

Two of those letters carry two tools each, and pressing the letter again moves to the second — so S S gets you the ellipse and L L the lasso.

The first four are about shape, the last two about colour. Which family you reach for depends on whether the thing you want has an edge you could trace, or a colour that distinguishes it.

The wand, and tolerance

Click with the wand and it spreads outwards from that point, taking in everything close enough in colour to where you clicked. Tolerance, in the tool options bar, decides how close is close enough.

• Low tolerance (around 10) — only very similar colours. Several clicks may be needed.
• High tolerance (50 and up) — takes in much more, and will leak into things you did not want.

Start low and raise it. Leaking is harder to notice than falling short, because the extra area is often somewhere you are not looking.

The wand also has a contiguous setting. On, it only takes pixels connected to where you clicked. Off, it behaves like By color and takes matching pixels from the whole picture.

Adding to and subtracting from a selection

Almost no useful selection is made in one gesture. The modifier keys combine them:

To do this	Hold
Add to the selection	Shift
Take away from it	Alt
Keep only the overlap	Shift+Alt

The usual way to select something awkward: take a rough pass with the wand, add the bits it missed with the lasso, and subtract the bits it over-reached into. Three imperfect gestures beat one careful one.

A selection can have holes in it, and the outline shows them.

The Select menu

Command	What it does
All	Selects the whole canvas
None	Clears the selection
Invert	Swaps selected for unselected
Grow..., Shrink...	Moves the edge outwards or inwards by a number of pixels
Border...	Replaces the selection with a band along its edge
Feather...	Softens the edge over a distance you give
Sharpen...	Hardens a soft selection edge
Remove holes	Fills in gaps the wand left inside the selected area

Invert is worth learning early. Selecting a subject against a plain background is often hard; selecting the plain background with one wand click and inverting is easy, and gives the same result.

Feather... creates partial selection coverage near the edge. Use it for gradual transitions; keep crisp edges for sharply focused objects. Judge a small radius at 100% zoom and at the final output size before increasing it.

Selections and masks

A selection controls the area affected by the next operation. An attached mask controls a layer’s visibility until you alter or remove it.

• Layer ▸ Mask ▸ Add mask from selection attaches the selection’s coverage to the active layer.
• Select ▸ Export ▸ Selection mask to layer... makes a separate greyscale layer representing the selection; it does not attach a layer mask.
• Select ▸ Import ▸ Selection mask from active layer creates a selection from layer coverage.
• Use Select ▸ Save selection... and Select ▸ Load selection... to keep a selection for later.

The usual pattern for a clean cut-out is: select roughly with the wand, convert to a mask, then refine the mask with a brush matched to the edge. Painting is more forgiving than clicking, and the mask is reversible in a way that deleting pixels is not.

Working through a selection

With a selection active:

• Painting is confined to it, so you can paint boldly right up to the edge
• Adjustments and effects apply only inside it
• Erase selected area clears what is inside
• Fill selected area... fills it with the foreground colour
• Copy takes only the selected pixels

The colour wash over the unselected part, when shown, makes it obvious which side of the fence you are on.

If something seems broken

Nothing happens when you paint. There is probably a selection somewhere else in the picture, possibly scrolled off screen. Press Select ▸ None and try again — this is the commonest confusion in any image editor.

A selection can extend beyond the visible viewport. Fit the whole picture or clear the selection before deciding that a missing outline means no selection is active.

The edge looks jagged. Feather it by a pixel or two, or turn on anti-aliasing in the tool options before making the selection.

The wand takes too much or too little. Adjust tolerance, and check whether contiguous is on.

Next

• Masks — making a selection permanent
• Painting and retouching — working inside a selection
• Transforming — cropping to what you have selected