For this next example I have chosen a mobile cell phone illustration I created last summer. Creating this new phone required the use of 20+ alpha channels, nearly 30 paths for masking (for each file), and a few bottles of Norton Mendoza 2004 Malbec Reserve. The creation process required nearly 10 iterations due to client and internal alterations. With so many changes, it was smart to build this "frankenstein" with smart objects. Recognizing the keyboard, dials, logos, and screen would require many rounds of "tweaks", I built each of those portions using Photoshop's smart objects. The final composite was a culmination of a base file template and the smart objects carefully masked. Any revisions during the "courting" process of color correction and retouch only required me to double click on the smart object (which opens the SO as a new temp file) needing the revision, create a new layer (for edit-ability, creative directors flip flop a lot), adjust the color, content, or component, and re-save the smart object. Photoshop smartly updates the placed (and embedded) smart object within our master file. Below you will see I have created an animated gif file showcasing some of the many alterations that occurred with this model. The actual file was a few hundred megabytes and much much larger when completed.
You can see quite a lot of masking, color correction, retouch, air brushing, and illustration was involved. Now imagine doing the same process across seven or eight files ! Here you can see many of the other views.
Color manipulation, color retouching, content management and structure, and consistent corporate branding become quite a challenge. The revision process combined with a well thought out workflow, involving smart objects, layer re-versioning, and consistent masking makes much easier work in Photoshop. The same processes with smart objects can be implemented in many aspects of digital assets. Business cards, fine art illustration, HDR blending of RAW files for extended dynamic range and noise minimization, commercial ads, the list goes on and on.
I used a smart object for the logo, another for the photo text, and a third smart object for the placed photo. You can update any of the componets by double clicking, or replace with another file completely by going to Phoshop's menu and selecting Layer/Smart Objects/Replace Contents, grab a new photo or logo and your finished. There are many uses for smart objects. I have only scratched the surface on the many possiblities. Try experimenting with them. You will be amazed with the versatility smart object functionality offers.