How to make a selection in a photo editor

Make, fix and use a selection in seven steps

1. 1

   Open the photo

   Go to lilcactus.app and choose File› then Open… (Ctrl+O or ⌘O), or drag the photo onto the window. To follow along exactly, open the sample photo from this page.

2. 2

   Drag a box around the jetty with Object Selection

   Right-click the selection tools’ button in the toolbar (or press and hold it) and choose Object Selection. Start at the left edge of the photo, just above the jetty’s far end, and drag to the bottom of the photo, just past the jetty’s right edge.

   AI running in your browser finds the object inside the box and selects it. On the sample it selects the deck and leaves out the posts.

   

   

3. 3

   Add the posts with Quick Selection

   Choose Quick Selection from the same toolbar button. Its Mode on the options bar (the strip under the menus) is Add, so whatever you paint over joins the selection. Press [ four times to make the brush 20 px, then paint one short stroke down each of the six posts. Quick Selection spreads to the edges it finds, so the strokes don’t have to be exact.

   Tip If a stroke spreads onto the water, hold Alt or ⌥ and paint over the extra part to take it away.

   

   

4. 4

   Check up close, and take the cone out

   Zoom in on the cone: press Ctrl+= or ⌘= a few times, then hold Space and drag until the cone is in view. On the sample, the cone’s upper gray-white stripe has joined the selection: it is gray like the wood. It would turn brown in step 7.

   To take the whole cone out, choose Object Selection again, hold Alt or ⌥, and drag a small box around the cone. Lil Cactus finds the cone and subtracts it, without touching the boards. Press Ctrl+0 or ⌘0 to fit the photo back in the window.

   

   

5. 5

   Soften the edge with Feather

   Choose Select› then Modify› then Feather…, type 2 for Radius and click Feather. Feathering blurs the selection’s edge, so the edit fades out over a couple of pixels instead of stopping in a hard line. Use 1–3 px for objects with crisp edges like this jetty, and much more for soft blends such as a vignette.

   

6. 6

   Save the selection

   Choose Select› then Save Selection as Alpha Channel. The selection is stored as a black-and-white channel called Alpha 1 in the Channels panel (beside Layers): white is selected, black isn’t.

   To get it back later, choose Select› then Load First Alpha Channel.

   

   

7. 7

   Use it: warm the wood, and save

   With the selection still active, choose Layer› then New Adjustment Layer› then Color Balance…; the dialog says “Applies within the selection”. Check that Midtones is selected, type 50 for Cyan – Red and −50 for Yellow – Blue, and click Apply. Only the jetty turns a warm brown; press Ctrl+D or ⌘D to deselect and see it without the dotted line.

   The adjustment layer gets a mask made from your selection, so the colors and the mask stay editable. To keep them and the saved selection, choose File› then Save As› then Lil Cactus Project… or Photoshop (.psd)… in the same submenu; after that, File› then Save saves to that new file. File› then Save on the JPEG would write a flat picture; the first Save of a JPEG, including the sample, opens the Save Image dialog.

   

   

Which selection tool to use

Tools that share a toolbar button are picked from it by right-clicking (or pressing and holding) the button.

Add, subtract and intersect

Object Selection, Marquee Select, the lassos and Magic Wand can change the current selection instead of replacing it:

• Hold Shift or ⇧ while you use the tool to add to the selection.
• Hold Alt or ⌥ to subtract from it.
• Hold Shift or ⇧ and Alt or ⌥ together to keep only the overlap of the old and new selections.

The same four choices are buttons on the options bars of Object Selection, Marquee Select, Lasso Select, Polygonal Lasso, Magnetic Lasso and Magic Wand. Quick Selection has no mode buttons: its Mode menu is Add or Subtract, and holding Alt or ⌥ subtracts while you paint.

Select menu commands worth knowing

• Select› then All (Ctrl+A or ⌘A) and Select› then Deselect (Ctrl+D or ⌘D). Select› then Reselect (Ctrl+Shift+D or ⇧⌘D) brings back the last selection.
• Select› then Inverse (Ctrl+Alt+Shift+F or ⌥⇧⌘F) swaps what is selected: select the sky, invert, and you have the landscape.
• Select› then Modify: Expand…, Contract…, Smooth…, Border… and Feather… reshape the edge by a number of pixels.
• Select› then Grow adds neighboring pixels of similar color; Select› then Similar adds similar colors anywhere in the picture.
• Select› then Transform Selection scales or rotates the selection outline itself, not the pixels.
• Select› then Quick Mask Mode (Q) covers the unselected area in red and lets you paint the selection: black protects, white selects. Press Q again to turn it back into a selection.
• Select› then Refine Edge… is for hair and fur: it searches a band around the edge for fine detail. How to remove the background from a photo walks through it.

Fix common problems

My edit changed the whole picture

Nothing was selected, or the selection was lost. Undo the edit with Ctrl+Z or ⌘Z, select the area again, and repeat the edit.

The edit stops in a hard line

The selection has no feather. Undo the edit, feather the selection 1–3 px, and edit again; or paint the adjustment layer’s mask with a soft brush.

Quick Selection keeps grabbing the background

Make the brush smaller and paint well inside the object. To remove a whole object it grabbed, Alt-drag a box around that object with Object Selection, as in step 4.

Object Selection selected the wrong thing

Press Ctrl+D or ⌘D and drag a tighter box around just the object you want.

Load First Alpha Channel is grayed out

The document has no saved selection yet. Save one with Select› then Save Selection as Alpha Channel first.

What to do next

• Hide the unselected part instead of editing it: layer masks.
• Change colors in one area only: adjustment layers.
• Remove the cone and the bin instead: remove an object from a photo.
• Cut out a person or product: remove the background from a photo.

Coming from another editor

Photoshop

Select › Save Selection… and Select › Modify › Feather…, with the Object Selection and Quick Selection tools.

GIMP

The Foreground Select and Paint Select tools, Select › Feather… and Select › Save to Channel.

Selections: questions and answers