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I have two layers and an alpha channel:

enter image description here

And I would like to select an area on the "Layer 1" with a contour from the alpha channel, namely I want the "red" area be inside the selection. Is there any way to do this?

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To load an Alpha Channel as a Selection....

Hold the Command/Ctrl key down and click the thumbnail for the Alpha Channel in the Channels Panel to load the Alpha Channel as a selection

Or.... Choose Select > Load Selection and pick the Alpha channel from the second dropdown list:

enter image description here


With the above in mind as to how to load a selection from an alpha channel....

For all selection methods... the Shift key will add to a selection, or the Option/Alt key will subtract from a selection.


So.. if a a selection for layer 1 is active....

  • to add the alpha channel (the red) to the active selection, hold down Command/Ctrl+Shift keys and click the Alpha Channel thumbnail in the Channels Panel.

  • to subtract the alpha channel (the red) from the active selection, hold down Command/Ctrl+Option/Alt keys and click the Alpha Channel thumbnail in the Channels Panel.


I, personally would merely use a layer mask....

  • Load the Alpha channel as a selection.
  • Highlight Layer 1 in the Layers Panel.
  • Click the Layer Mask button on the bottom of the Layers Panel to add a layer mask to Layer 1.

You can then select, paint, filter - whatever - on the mask which can often be easier than figuring out the right key combos, inverse for a channel, and procedural steps in order to get a selection of exactly what you need.


If you don't want a full Layer Mask, you can utilize the Quick Mask Mode -- load the Alpha Channel as a Selection, then tap the Q key on the keyboard, there's then a Quick Mask (by default you'll see red everywhere that is not part of the selection - red means "hide" in Quick mask). Just paint - black for hide, white for show. You can make selections, run filters, etc all in quick mask mode as well.When you're done, just tap Q again and you'll have a selection.


Truth is, there are numerous ways to create then add to or subtract from a selection. Which one works best in any given situation will vary.

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  • Thanks a lot! I just needed to get a selection on the "Layer 1" to work with it. Aug 25, 2023 at 17:06
  • Ahh, then I may have gone overboard in explaining :) oh well, more info never hurt anyone.
    – Scott
    Aug 25, 2023 at 17:17
  • Completely agreed with you! Aug 25, 2023 at 17:33

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