How can I cleanly mask a subject and thin rope in Affinity Photo?
Asked 1/10/2021
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2 answers
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I'm using Affinity Photo 1.8.5 on Windows 10 and want to keep only the child and the green rope, masking everything else in the image. I tried the Selection Brush Tool and Flood Select Tool, but around the rope, leg, and fine edges it becomes extremely slow and inaccurate, with pixels being removed that should stay. What's a better way to make a clean mask for this kind of subject, especially with thin details like a rope and small stray hairs?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
5y ago
2 Answers
4
This might not be the fast and convenient answer you're looking for but IMO this is the only way to get a clean selection of your subject:
- Use the Pen Tool to draw a path just on the inside edge of what you want to keep. In the case of this image I had to draw three paths which I then combined using the
Layer > Geometryactions. - Then offer the newly created path to the image layer as a mask.
- Open the Layer effects panel for that path and set the
Gaussian Blurproperty to0.2 px(which smooths the edges slightly) - Add another mask layer above the path layer and use the Paint Brush Tool to remove any unwanted areas which are too vague for a path (such as the one strand of hair that separates from the rest).
This is a somewhat uncommon technique as you would normally use the path to create a selection and then refine that selection and finally output it as a mask but personally, I like the fact that you still have the flexibility of the path/vector to tune the curves of the selection.
Originally by user71657. Source · Licensed CC BY-SA 4.0
user71657
5y ago
0
Generated from our catalog & community — verify before relying on it.
For this kind of image, automatic selection tools usually aren’t the best choice. A cleaner approach is to use the Pen Tool to draw a precise path around the subject, keeping the path slightly inside the edge of what you want to keep. If needed, create multiple paths and combine them with the Geometry operations.
Then use that path as a mask for the image layer. To soften the cut edge slightly, apply a very small Gaussian Blur to the mask/path edge (for example, around 0.2 px).
For areas that are too irregular for a path—such as stray hair or tiny edge corrections—add another mask layer and use the Paint Brush Tool to paint those areas in or out manually.
So, instead of trying to flood-select pixel by pixel, use:
- Pen Tool for the main outline
- Combine paths if necessary
- Apply the path as a mask
- Slightly feather/blur the mask edge
- Refine tricky details with brush painting on a mask
This is slower than one-click selection, but it’s the most reliable way to get a clean result with thin objects like the rope.
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