A selection limits where an edit lands. Paint, fill, adjust or delete with a selection active and only the selected pixels change.

PhotoTux’s selection is a pixel selection — a greyscale mask rather than a path — so it can be feathered, blurred and painted, and it converts cleanly into a layer mask.

Drawing a selection

Every selection tool is on the shelf, in the second band from the top.

Tool Shortcut Draws
Rectangular Marquee M A rectangle.
Elliptical Marquee Shift M An ellipse.
Lasso L A freehand outline; releasing closes it.
Polygonal Lasso Shift L A polygon, one click per corner.
Magic Wand W Everything contiguous with the clicked pixel and close to it in colour.
Color Range Shift W Everything in the layer close to the clicked colour, contiguous or not.

For the wand and Color Range, the options bar carries a tolerance — how far from the seed colour still counts. Low tolerance picks a narrow band of colour; high tolerance takes most of the image.

Combining selections

The options bar has four modes, and they are the standard ones:

  • New replaces whatever was selected.
  • Add unions the new shape with the existing selection.
  • Subtract removes it.
  • Intersect keeps only the overlap.

The whole-selection commands

Command Shortcut
Select ▸ Select All Ctrl A
Select ▸ Deselect Ctrl D
Select ▸ Invert Selection Ctrl Shift I

Modifying an edge

Select ▸ Modify holds five operations. Each opens a prompt asking how far, because for feathering especially the radius is the operation.

Operation What it does
Feather… Softens the edge over the given radius, so an edit fades in rather than stopping abruptly.
Expand… Grows the selection outwards.
Contract… Shrinks it inwards.
Smooth… Rounds off jagged edges and drops stray specks — useful after a wand selection on a noisy photograph.
Border… Replaces the selection with a band straddling its edge, for outlining.

Contract then feather is the usual recipe for a clean composite: pull the edge in by a pixel or two so you are not carrying a halo of background, then soften what is left.

Selections and masks

The two are the same kind of thing — a greyscale coverage map — seen from two places. A selection belongs to the document; a mask belongs to a layer.

  • Select ▸ Selection to Mask writes the current selection into the active layer’s mask, so what you selected is what stays visible.
  • Select ▸ Mask to Selection loads the active layer’s mask back into the selection, so you can modify it with the tools above and write it back.

That round trip is how you edit a mask with selection tools instead of with a brush.

Painting a mask

A mask can also be painted directly. Select the layer’s mask in the Properties panel and paint: black hides, white shows, grey is partial. The Brush, Gradient and Paint Bucket all work.

A gradient painted on a mask is the standard way to fade one layer into another — a linear black-to-white gradient across a mask hides one end of the layer and shows the other.

Copying and pasting through the clipboard

The clipboard carries three different things, and the Edit menu names each one:

  • Copy (Ctrl C) — the selected pixels.
  • Copy Selection Mask — the selection itself, as greyscale.
  • Copy Layer Mask — the active layer’s mask, as greyscale.

And three ways back in:

  • Paste as New Layer (Ctrl V)
  • Paste as Selection — treats what is on the clipboard as a selection.
  • Paste as Layer Mask — writes it into the active layer’s mask.

That is more explicit than a single Paste that guesses, and it is why pasting a screenshot into a mask does something predictable.

What a selection affects

  • Painting is clipped to it.
  • Fill and Gradient apply within it.
  • Delete clears the selected pixels of the active layer.
  • Filters apply within it.
  • Adjustment layers ignore it — they apply to everything below them. Confine one with a clipping mask or by writing the selection into the adjustment’s own mask.