If I have two images, one with a transparent object overlay and one without but that are otherwise identical, how can I extract the transparent object?
Example: given the first two squares, how can I get the last one?
Graphic Design Stack Exchange is a question and answer site for Graphic Design professionals, students, and enthusiasts. It only takes a minute to sign up.Sign up to join this community
Put the image without the transparent square, perfectly aligned on a layer on top of the one with the square and set its blending mode to 'Divide'. Easy.
More information on the different blending modes can be found here:
If you want your square on a transparent background, you can use the square as a layer mask on itself. The result from this won't be perfect (i.e you won't get the exact transparency level as the original) but it will get you very close with some adjustments.
First Select All and Copy Merged.
Paste on a new layer and with your new merged layer selected, add a new layer mask.
alt + click the mask thumbnail to edit the mask.
cmd + I to invert the mask (black masks, white reveals).
You will need to manually adjust the mask using levels/curves etc. so that the transparency matches the original.
Click anywhere other than the layer mask thumbnail in the layers panel to stop editing the layer mask and see the result.
If the image is flat, you can't. If you have the layered PSD, then it's pretty easy and there are a few ways you could do it.
One way is to select the transparent object you want to isolate, by ⌘ + Clicking on the layer's icon in the Layers Panel.
With your selection made, go to Image > Crop
Deselect your layer (⌘ + D) and then delete everything else in your document, so only your desired layer is left
Save in a format that supports transparency, PNG for example.