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How can I select the convex hull of an existing selection in Photoshop. In other words, how does one fill the holes in a selection in Photoshop?

Consider a donut shape. You use the wand to create a selection of the donut shape, but the hole of the donut remains unselected. Is there a tool or sequence of actions to fill the "donut holes" in a selection, preserving the precision of the outermost selection lines?

This same question was asked previously, but for Gimp.

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You can hold down the Shift key and use any selection tool to add to an existing selection.

You can also hold down the Option/Alt key and use any selection tool to subtract from an existing selection.

You could also switch to Quick Mask Mode and use painting tools to "paint" your selection.

You could also create a Layer Mask of the current selection, then paint on the layer mask.

You could also Save the Selection via Select > Save Selection, then paint on the alpha channel which is created in the Channels Panel.

The Photoshop help files may be enlightening for general operations such as this.

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    Thanks @Scott. Definitely familiar with some of these approaches, just thought it could be performed automatically. Given an outermost selection perimeter, it seemed there'd be a way to simply include any unselected areas within that perimeter. A friend says the terminology I'm looking for is the "convex hull" of the selection. – Dan Lugg Oct 24 '15 at 17:25
  • This question is definitely in the same vein, just the wrong application. – Dan Lugg Oct 24 '15 at 17:29
  • @DanLugg I don't think it can't be much simpler than the options Scott gave you, unfortunately! And Johannes trick with the inverse is also very clever and even faster in some situations. Other tricks include to "select similar" in the "select" menu, and inverse the selection, and/or combine all the tricks above to this too. It depends on what you need to achieve. – go-junta Oct 25 '15 at 0:32
  • It's a legitimate question, no need for arrogant sarcasms like "The Photoshop help files may be enlightening for general operations such as this." :P In your solutions, you have to PAINT (not in a creative manner at all) and sometimes is time consuming and annoying, when you think other applications have this feature - even the ugly Corel Photopaint (Remove Holes): coreldesigner.files.wordpress.com/2008/10/ppmask-13.jpg Look at those clouds from the Gimp link, or imagine you have a complex white shape with a dark-green pattern, on a dark-green non-uniform background... How do you selec – Robert K. Jan 24 '18 at 8:00
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You may consider using the Quick Select tool instead of the magic wand. It keeps adding to the selection and it will be a simple matter of dragging it inside the donut and continuing into the empty center. This tool is in the same tool well as the Magic Wand.

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What I would do is first save my selection, then select the inverse of the selection with Select > Inverse or ctrl + shift + i.

In the case of the donut this will select the inside hole of the donut and everything outside of the donut. Now fill in the selection. Obviously you don't want everything on the outside filled too, so we will now remove this by subtracting the inside of the donut from the selection and then clicking Delete to clear all the fill from outside of the donut.

This should leave just the inside of the donut filled in.

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Does this help? Select the outer side of the donut (on the layer mask) with the wand tool (with a high tolerance, sample only contiguous pixels) and then simply invert the selection.

  • What about the donut hole? if you invert your selection, it selects the hole and the donut. So not a solution to the problem – Luciano May 3 '17 at 13:09
  • @Luciano It does solve the problem (I want the donut + hole(s)) however it won't work in many cases, such as if the area surrounding the donut is noisy. It could work sometimes, but I was hoping rather than having to invert an outer-selection, I could fill in the inner-selection. – Dan Lugg May 5 '17 at 5:05
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I use GIMP for this. Open the PSD in gimp, select the layer with holes (in gimp ALT+click on layer), then select -> remove holes. Then fill the new selection with a color. then select -> inverse, and fill with another color. Then layer -> to image size. Then copy (CTRL+C). then switch back to photoshop, and paste. remove the bg color with the wand. And you have a layer with the convex hull.

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I usually make Quick selection from basic selection with holes, then make selection with Magic Wand in OUTER space of donut (It will select all background). Then invert selected area (Ctrl + Shift + I) and fill this selection. Finally just Unselect Quick selection, and You have selected ALL internal areas in All donuts (It works just if donuts does not overlay all background, or are distinct from each other). This often solves the situation with one or few clicks, even for complex scenes (not only donuts :-).

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