It's always a good idea to save a layered version of your digital project so that you can make changes later or use a layer in another project. Sometimes, however, you want to open a project just to print or look at it. Here’s a quick way to open your layered file as one layer:
Open Photoshop or Elements.
Select File > Open or press Ctrl O (Mac: Cmd O) on your keyboard.
Browse to find the layered file on your computer.
Click to select the file.
If you were to simply click Open at this point, you’d have to wait for all of the layers to populate.
Depending on the number of layers and the speed of your system, this can take a while, bogging down your computer.
Instead, hold the Shift and Alt keys (Mac: Shift and Opt keys) as you click Open.
A dialog box will populate asking if you want to open the composite. Click OK.
Your layered file will open as one flattened layer that you can view and print.
Be careful not to overwrite the original with the flattened layer while working with the composite. Just close without saving.