Photoshop Smart Objects: What are they and why should you use them?
Smart Objects lie at the root of all non-destructive edits in Photoshop. Non destructive editing is the process of editing your image in a way that allows you to easily go back and change something without degrading the image quality. Non destructive editing techniques are import to learn for many reasons. Many photographers may argue that they always save a copy of their image after editing in Photoshop, therefor eliminating the need for non destructive editing. However, I always recommend saving a copy AND using non destructive editing techniques. Have you ever been in the position where you reviewed a photo the next day and it didn’t quite look right, but you had to go back and restart the edit to fix the problem? Or even worse, you had to add another layer on top to fix the effect, which then lowers the image quality. This has happened to me too many times, and therefor, I began using smart objects and editing non-destructively (mostly).
A Smart Object is a layer that allows you to keep your edits separate from the photo itself, which allows for non-destructive editing as well as easier access to your file to go back and change something that may need to be fixed later. In my workflow, I generally nest two things on a Smart Object. First, I use the Camera Raw Filter on the smart object. By using it on a Smart Object (or in Lightroom) rather than on a regular background layer, I allow myself the ability to go back and change the Camera Raw Filter. For example, if I decide that I increased the exposure too much, I can easily double click to go back to Camera Raw. This is much better, and less destructive, than making a new layer and then doing a completely new Camera Raw filter. The second thing I use the Smart Object for is any other filters I use. I frequently use either the Nik Collection or the On1 Effects filters, so these live here. Again, this allows me to double click and edit the effect, which is especially helpful on something complicated like a filter. Many of the effects of the filters I use would be nearly impossible to make a new layer over the top to fix, so having the ability to go back and change them easily is so valuable.
Now that you have an idea of what a Smart Object is, let me show you how to use it.
I've colored the layers that are non-destructive with green, and the destructive layers are red. I had to use some destructive layers for certain effects that I wanted, but notice that I did those last. If I wanted to change something on any of the green layers, I'd have to delete all of the red and go back down. However, I organized my file so all of the destructive layers are on top. To go back on the edits on any photo you've made, you'll want to wait to apply the destructive edits last.
The bottom layer is the Smart Object (DSC02714). You can tell that it's a smart object by the small grey box on the image, as well as the "Smart Filters" layer mask that appears. If you open your file as a Smart Object from Lightroom, any edits you applied in Lightroom will carry over, which you can further edit in Photoshop.
To open a photo as a Smart Object in Photoshop, go to Photo > Edit In > Open as Smart Object in Photoshop.
If you've already loaded the photo into Photoshop as a regular layer and not a Smart Object, you can convert it to a smart object by going to, Layer > Smart Objects > Convert to Smart Object.
Now, you're able to put any filters on this smart object that you'd like. I recommend using the Nik Collection or On1 Effects to add the desired filters, and since you put them on a smart object, they'll be directly editable. On a photo like this one, if I wanted to go back and edit one of the filters on my Smart Object, I would have to delete all of the layers that I colored red, but I make those layers last, and they're the least time consuming, so I have no problem recreating them.
On the next photo you edit, play with smart filters. You'll find them especially helpful once time goes on and you find yourself with more editing skills. Having the ability to go back and make changes, rather than restarting from the bottom will save you lots of time and allow you to find the things that you're doing wrong much easier.
Good luck with using Smart Filters in your post processing!