Selections

Five selection tools, which to use

Rectangular / elliptical marquee: regular shapes. Hold Shift for square or circle

Lasso: freehand any shape; releasing closes it

Polygonal lasso: click point by point for straight edges, double-click to close

Magnetic lasso: snaps along colour boundaries. Best when subject and background contrast clearly

Magic wand: click once to select a whole similar-coloured region; tolerance sets the range

High-contrast subjects (a product on white) → magic wand is fastest.

Complex edges with similar colours (hair, fur) → magnetic lasso is more accurate

Adding, subtracting and feathering

Three modes

The selection toolbar switches between new selection / add to selection / subtract from selection.

Or use the shortcuts: hold Shift while dragging to add, Alt to subtract.

Feather

Feather softens the selection edge so composites do not show a hard seam.

Use 1~2 px for cut-out portraits, 20~50 for glow effects.

Select all and invert

Ctrl+A select all, Ctrl+Shift+I invert. To change the background but not the subject, inverting is fastest.

Made a wrong selection? Ctrl+D clears it, or press Esc

Cutting out and swapping the background

Steps

1. Select the subject with the magic wand or magnetic lasso

2. Feather 1~2 px, no more

3. Copy the selection to a new layer

4. Place the new background underneath

5. Check the edges. Any white rim: contract the selection and redo

Common problems

White rim → the selection is slightly larger than the subject. Contract 1~2 px and redo

Soft, hazy edge → too much feather

Veils and stray hairs will not cut cleanly → genuinely hard. Cover it with a soft glow instead

Think about post-processing while shooting: frontal, shoulders level, ears and eyebrows visible, stand against a white wall.

Do those four things and cutting out gets twice as easy

What you can do inside a selection

Once a selection exists, almost every later operation is confined to it:

Brushes paint only inside; anything outside is blocked (excellent for clean colour blocks)

The bucket fills only inside

Filters apply only inside

Copying, deleting and colour adjustments affect only the selection

To brighten one part of a photo: select it → feather 20 → adjust brightness.

That is local adjustment without needing a mask