There's always another layer to discover in Photoshop! I hadn't used Smart Object stacking before and was recently introduced to it at a conference. The stacking modes have mysterious terms like Entrophy, Kurtosis and Summation (Read Adobe's technical explanation of stacking modes here).
Some of the practical applications of Smart Object stacking:
- If you take multiple photos of the same road or fountain and then use stacking mode Median, you can remove moving objects like cars and people (layers must be aligned first)
- If you take photos of the same room with different light sources use the stacking mode Maximum to combine the light of all of these sources (layers must be aligned first)
How to use Smart Object stacking:
- Open a new document in Photoshop. Drag in at least 2 images. Select the images in the Layers panel, right click and Convert to Smart Object.
- Select Layer > Smart Objects > Stack Mode and choose a stacking mode.
- If you don't like the results, repeat the previous step to choose another option. Unfortunately, I couldn't find a keyboard shortcut or simpler way to access these options but you could always create custom keyboard shortcuts if you end up using this feature a lot.
I had fun playing around with these 2 photos and different stack modes as a creativity tool to see the different results.
Stacking mode: Summation
Stacking mode: Range
Stacking mode: Maximum
Note: Once something is converted to a Smart Object there is no way to ungroup it (at least that I could find in my research) and release all of the original layers (the way you can ungroup layers). To get back to the original contents, open the Smart Object and drag all the layers back into your document. Then delete the Smart Object.