Smart Objects first appeared in Photoshop CS2, and represented a huge innovation for Photoshop users. A Smart Object essentially wraps up an entirely new copy of a source ﬁle and stores it inside the Photoshop document as a layer. This meant the source files for a Smart Object always traveled inside of the Photoshop document and never got lost. Smart Objects allowed embedding of things like Illustrator vector art, PDF files and Camera Raw files, and had them remain editable anytime down the road. (Linked Smart Objects are new to Photoshop CC, and allow linking rather than embedding of the original RAW ﬁle, reducing ﬁle sizes.)
In the case of the camera’s RAW files, you would first open the photo into the plug-in and make all the regular adjustments you think you might need. Then, rather than simply rendering the RAW data into a regular RGB ﬁle, holding down the shift key changes the Open Image button to Open Object, and clicking that creates the Smart Object layer. (Creating a Smart Object can also be set as the default in the Workflow Options dialog.)
RAW ﬁle Smart Objects give you an incredible amount of ﬂexibility in your workflow. For instance, at first, you might place the RAW ﬁle using the processing defaults simply for positioning or comping purposes. Then, later, if you want to change the look of the RAW image, you can do that. Double-clicking the Smart Object icon opens the embedded ﬁle in Camera Raw again, allowing you to essentially reprocess the RAW for an entirely different look, all the while preserving the exact position, scaling and filters that you applied to the original.
All of which finally brings us to Smart Filters. Smart Objects were a huge innovation in nondestructive workflows, but you couldn’t paint or run Photoshop filters on them in the same way that you would an ordinary layer. To do anything more than transform a Smart Object, you would have to "rasterize" it first, thus discarding its nondestructive qualities. Smart Filters came along in CS3 and solved that problem by working nondestructively on Smart Objects.
Then, to add chaos to mayhem, Photoshop CC came along with the new ability to run Camera Raw as a filter! In the case of an ordinary RGB layer or selection, Camera Raw can act just like any other filter, changing the pixels forever. But if you run it as a filter on a Smart Object, ACR becomes a Smart Filter. So you can now have a nondestructive filter acting on a Smart Object, which has its own nondestructive attributes! For beginners, I think you can start to see how learning to use all this stuff could be a bit of a challenge. So let’s summarize. You can now use the ACR plug-in three entirely different ways in Photoshop:
1) To process a RAW ﬁle into RGB for further editing or printing in Photoshop
2) To change the processing of a RAW Smart Object as a layer in Photoshop
3) As a filter on any layer (Smart Object or otherwise) or a selection in Photoshop
Let’s start with Case #1: processing a RAW ﬁle into RGB. This is the base case, and it’s the most important because the RAW ﬁle contains all the original information from the capture, with the data stored in its most pure form. To view or use the RAW image in any way, it must be transformed into an entirely different format, usually RGB (Fig. 1).
There can be many interpretations of any given RAW photo into RGB, and there’s no "right" or "perfect" rendering. It’s always an interpretation that’s pretty much a one-way street, meaning it’s a destructive process, which is why we have Smart Objects.
When you change your mind about how you want your photo to look, going back to the RAW data always gives you the most ﬂexibility. But if you’ve made transformations to the image in Photoshop or applied filters to it, going back to the RAW data can be difficult, or impossible if you’re the designer and don’t have access to the original RAW ﬁle.
Which brings us to Case #2: ACR can be used to change the processing of a RAW Smart Object in Photoshop. Once you’ve created a Smart Object layer, you can reopen ACR and edit it at anytime, starting with the original source data again, to change your interpretation (Fig. 2).
Editing a RAW Smart Object literally reprocesses the image from the original embedded ﬁle, creating an entirely new set of RGB pixels for the layer in Photoshop—without disturbing any scaling or filtering you might have done previously! This is important because going back to the source ﬁle gives you access to all of the original color and tone that exist in the RAW data before processing. This becomes much easier to see when we come to Case #3: using Camera Raw as a filter.
There are already about 100 different ways to adjust color in Photoshop, so why add the Camera Raw plug-in to the filter menu? I don’t have any inside information on the subject, but my personal view is that many photographers and designers simply find Camera Raw to be a more efficient way to correct photos. All the tools are in one place, and Camera Raw does bring new functionality to the party, such as the Clarity control and a true White Balance control. And because many photographers have taken the time to really learn Adobe’s RAW processing controls, this brings those same familiar controls into Photoshop for use on any layer or selection, which is genius.
Having said that, I’ll add that you do have to be careful when you use Camera Raw as a filter. Unless it’s used as a Smart Object editor, ACR always works on the RGB data in the layer. It can’t access the original RAW pixels. This may seem like a merely technical distinction, but it goes to the heart of why Smart Objects matter. Being able to reprocess the original RAW data can make a huge difference in the final image quality.
Here’s an example. If you’re exposing to the right (ETTR) when shooting RAW, you might end up with an exposure like the one I captured photographing a hawk over Big Sur. And this is what the RAW capture would look like if it were simply placed into a Photoshop ﬁle as a Smart Object using the ACR defaults (Fig. 3).
Exposing to the right is a technique of capturing the brightest tones up as high as possible in the dynamic range of your sensor, where you have the most capture bits available. The downside is that ETTR can leave you with flat, washed-out highlights until you bring them back down into their normal relationship to the midto
nes during processing. Once placed for size and position, before publishing you’d go back and reprocess the RAW file to finesse the final image. When you double-click the Smart Object, you’re accessing the RAW data in Camera Raw again, and applying a few quick settings enables you to bring out the true highlight detail contained in the capture (Figs. 4, 4a).
The fact that you’re going back to the actual RAW data in the Smart Object is the only reason why you’re able to pull out such a striking amount of detail from the highlights. This is in stark contrast to what’s possible when using Camera Raw as a Smart Filter on the very same layer. Rather than double-clicking the Smart Object icon to access the original RAW data, this time I’ll select the layer and choose Camera Raw from the Filter menu (Fig. 5).
This opens the layer in Camera Raw, and at first everything looks the same. Go ahead and apply the very same set of settings. This time Photoshop creates a Smart Filter for the nondestructive Smart Object layer because it can’t actually modify the object. It only has the pre-rendered RGB pixels in the layer to work with, so this is what you get (Figs. 6, 6a).
Camera Raw does its best to pull out detail with the Exposure and Clarity settings, but the end result is almost unusable compared with what we were able to achieve working from the actual RAW data in the Smart Object. The highlights are flat and muddy because they were all compressed together up into the very brightest part of the range in the original. Once compressed in that way in an RGB space, it’s impossible to pull them apart again to yield the same amount of detail. This is exactly the same problem you have when shooting JPEG, where the compression of the highlights is essentially done for you in the camera. Once the RAW sensor data is compressed and rendered into an RGB space, you have much less ﬂexibility in the changes you can make in tonality, even when using Camera Raw as a filter.
You can go to mulita.com to find George Jardine’s extensive tutorials on Lightroom and his blog.