You’ll find ‘selections’ and ‘masks’ turning up constantly in any talk about photo-editing. They both do the same thing, isolating an area of a photo so that it can be adjusted or modified separately to the rest. In non-destructive photo-editing software these are often called ‘local adjustments’.
So what’s the difference?
Selections are typically short term. You create a selection around an object or area, make your adjustments and then discard the selection because you don’t need it any more.
Masks are more long-term. You can use a mask to do the same job as a selection, but masks are typically saved within the image, either attached to an adjustment layer (Photoshop, Capture One, Exposure X, for example) or as as a mask in its own right with adjustments attached (DxO PhotoLab, Lightroom.)
The idea of a mask is that you might need it again later, either to change the adjustments you made or to modify the mask itself to blend in better or follow your subject’s outline more closely.
These are some typical examples. Different programs offer different selection tools. These are the tools you get with traditional photo editors like Photoshop and Affinity Photo.
Lasso tool: This is a freehand tool you use to draw manually around the area you want to select. You need a steady hand and while it’s a quick way to make selections it’s not very precise.
Polygon Tool: You can use this to follow object outlines manually with a series of straight lines. It can be the most effective way to select man-made objects with clear, simple edges.
Magnetic Polygon Tool: This is like the regular polygon tool in Photoshop, but it ‘magnetically’ latches on to object outlines. You still click to add points manually, but the tool follows the outline in between.
Magic Wand tool: This is a simple eyedropper that selects areas of similar tone to the point where you click. It’s a quick and dirty tool but can be very effective on skies or other areas of similar tone. There is a ‘Tolerance’ setting with this and other tools that you can use to adjust the sensitivity.
Selection Tool/Brush: This newer and more sophisticated kind of tool that is like more advanced magic wand that closely follows object outlines at the same time. You brush or click over the area you want to select.
In traditional photo editors like Photoshop and Affinity Photo, selections and masks are interchangeable. You can turn a selection into a mask if you want to save it for future use within the image. These are ‘raster’ masks because they’re made up of pixels.
Non-destructive editors like Capture One and Lightroom use ‘parametric’ masks, which define an area, not specific pixels. These are not quite as definite or precise but much easier to create and adjust later.
Brush Tool: A simple freehand brush which you use to paint over the areas you want to mask. You can change the size of the brush, its opacity, its ‘hardness’ and often its ‘flow’ rate.
Gradient Mask: These are typically used to darken bright skies but can be used for many other tasks too. One side of the gradient line is adjusted, the other side is left unadjusted and there’s a graduated zone in between to blend in the adjustment.
Radial Mask: This is like a gradient mask, but circular, so the area outside (or inside) the circle is adjusted but the part inside (or outside) is left unaltered, and in between is a gradual transition.
Selection and mask adjustments
Different programs offer different selection and mask adjustment tools, but here are two key ones.
Feathering: This can be applied to both selections and masks. It’s used to soften the edges of the mask to make them less obvious and to prevent obvious ‘steps’ between adjusted and unadjusted areas.
Luminance masks: These are common in non-destructive photo editors that use ‘parametric’ masking. You can set the mask to automatically mask areas brighter or darker than a certain tone and exclude the rest.
Selection and masking: 3 things to know!
- The first is choosing the right tool for the job. No one selection tool is better than any other – each has its own advantages in different situations
- Using the tool in the right way. If you’re struggling to get a good selection, it might be because you need to swap tools
- Some subjects and scenes are easier to mask than others, and some are so difficult that you may have to accept that you’re never going to mask them successfully. So step 3 is knowing when to give up!
- Local adjustments explained
- The Lightroom Select Subject mask tool and how it works
- Five quick masking tips to save time and get better results
- How to mask effects in ON1 Photo RAW
- The power of adjustment layers and masks
- Exposure X7’s new Selection tool is pretty remarkable
- How to add a new sky to a landscape without selections
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