Today’s Question: Will a saved selection continued to be saved once Photoshop is turned off for the day and back on the next morning? I ask because when I turn Photoshop back on in a subsequent session I cannot find any of the previously saved selections.
Tim’s Quick Answer: Saved selections will only be saved “permanently” if you are saving them as part of a compatible image file format, such as TIFF or PSD. If you save a selection for an image file that does not support saved selections (such as a JPEG image) then the saved selection will disappear if you close the image without also saving it as a TIFF or PSD file. You can see saved selections by choosing Select > Load Selection from the menu, or by looking at the Channels panel.
More Detail: When you save a selection in Photoshop, such as by using the Select > Save Selection command, the selection may not be saved permanently. Photoshop stores a saved selection as an “alpha channel”, and not all file formats support alpha channels.
So, if you open a JPEG image, save a selection, and then save the image and quit Photoshop, you didn’t actually save the selection. That is because JPEG images (among other image file formats) don’t support alpha channels.
The TIFF and Photoshop PSD file formats do support alpha channels, and therefore are able to preserve your saved selections as part of the file. That means you can save a selection for a TIFF or PSD file, save the updated version of that file, and the next time you open the image in Photoshop you’ll be able to load the selection again.
Note that you can view a list of saved selections by choosing Select > Load Selection from the menu and clicking on the Channel popup. You can also view the alpha channels for the saved selections (which provides a thumbnail view of the mask for the saved selection) by going to the Channels panel (Window > Channels).