Refine selections in Quick Mask mode

Tired of painstakingly clicking around an image trying to include just the right pixels in a selection? Have you heard about Quick Mask mode, but didn’t know how to use it? In Adobe® Photoshop® CS you can accurately—and easily—refine selections using the Paint Brush tool in Quick Mask mode! Follow along in this tutorial to learn how Quick Mask mode works, and some of the ways you can use it.

1. Make a selection.

Make a selection in your photo using any of the selection tools. In our example, we made a selection using the Lasso tool. Instead of carefully selecting with the Lasso tool and feathering the selection edge, we made an exaggerated rough selection that we can then perfect in Quick Mask mode.

2. Switch to Quick Mask mode.

In the toolbar, click the Quick Mask button. Your image is overlaid with semi-transparent red—except for the selected areas. You can change the opacity of the red overlay by double-clicking the Quick Mask button, and then typing in a new Opacity percentage in the Quick Mask Options dialog box.

3. Refine your selection.

Select the Paint Brush tool. Choose a soft brush, and make sure that your paint brush opacity is 100%. When you are in Quick Mask mode, the paintbrush paints on the red mask and not on your image. You can paint only in black, which subtracts from the selection; white, which adds to the selection; or shades of gray, which partially select pixels.

Here we chose black as our foreground color to subtract from the original selection (adding to the red mask). You can paint with white to add to a selection, whenever necessary, removing part of the red mask.

4. Create a feathered selection as you paint.

We chose a soft edge brush, so as we paint we get a soft edge to our selection. The effect is that we are painting the edges of the mask with gray paint.

The real power of Quick Mask mode is that you can paint with any shade of gray to partially select pixels. When you make an adjustment on partially selected pixels, you get a partial adjustment on those pixels. This creates smooth transitions between the selected and unselected areas.

In Standard mode, you can’t see the partially selected pixels of a feathered edge in your selection. Pixels that are less that 50% selected are outside of the marching ants view of the selection.

In Quick Mask mode, not only can you see your feathered edge as you create it, but you can also quickly edit it.

5. Save your selection.

After you’ve made and refined a selection it’s a good idea to save it so that you can reuse it if you need it again later.

Choose Select > Save Selection. Make sure that the current working document is displayed in the Document menu. Choose New in the Channel menu, type a name for the selection, and click OK. In the Channels palette, you can see your selection saved as an alpha channel.

For more information on saving selections, see Photoshop Help.

6. Modify the selection using an adjustment layer.

Now that you have a precise selection, you can perform an isolated tonal correction to the image. To do this, create an adjustment layer.

In our example, we chose Layer > New Adjustment Layer > Levels and clicked OK in the New Layer dialog box. Then we made our adjustment in the Levels dialog box. We adjusted the Levels gamma slider to lighten the selected area.

When you choose any new adjustment layer while part of the image is selected, Photoshop creates a layer mask for the adjustment layer. The layer mask confines the adjustment to the selected area. If you need to refine the mask, you can click its icon in the Layers palette, and then use the same painting techniques that you just learned for working in Quick Mask mode.

For more information on using adjustment layers and layer masks, see Photoshop Help.