I've been meaning to do this comparison for a while. I've received several questions about managing large files. PSD files are notably larger than RAWs or JPGs. As more and more of your photos go through the Perfect Photo Suite, storage space may become a concern. I became curious... can Smart Photos reduce file size since it's storing instructions on how to change an image versus actual pixel changes?

EXECUTIVE SUMMARY

Use Smart Photos, it'll save you storage space.

Smart Photos produces smaller PSD files for what I'd consider a typical editing session in Suite 9. You'll save ~15% storage space. I use Smart Photos for the re-editiability feature... the disk space savings is an added benefit. There's more numbers and breakdowns below.

The major question I've been asked is "How do you manage these large files?" In short, I ignore the file size. Storage is relatively cheap and file sizes won't prevent me from using the tool chain that will get me the best results. I use 16-bit PSD. I keep the PSD files for my very best work. I choose the flexibility of being able to re-edit at any time over the storage uptick.

If you are tight on storage, a compromise is using 8-bit PSD. That will save 50% or more compared to 16-bit.

Also, if you need to reap disk space, you can convert a stylized image to a high quality JPG and eliminate the PSD. I occasionally do this for "lesser" images, but it's rare. Aperture's search tools can quickly identify large PSD files, and I suspect Lightroom can as well. Other steps you can take to cut down on storage usage is cull images and get rid of the cruft early in workflow. 

Of course, only convert when you are certain you are finished editing the photo. Never delete the RAW image. That's your digital negative.

Experiment 1 - Vanilla Round-Tripping

As soon as I leave Aperture and the file transforms from RAW to PSD (or TIFF for that matter), the files grow an order of magnitude in size. Same is true for Lightroom. It's a function of the file format. A quick and dirty experiment of round-tripping a Nikon D7000 RAW file of ~19MB from Aperture to the Perfect Photo Suite with zero editing.

Granted, these are pretty meaningless measurements. There's no point in sending an image to the suite if you're not going to modify it in some ways. However, it does illustrate the growth in size simply by changing the file format.

Also, it's very clear you pay a premium for using 16-bit file formats.

Experiment 2 - Real World Editing

For a typical edit, my PSD images average ~400MB. For more complex edits requiring more layers, reaching a 1GB file is not uncommon. The next experiment is more meaningful. It mimics a typical editing session for my photos. Here's the rundown:

• Send a RAW file from Aperture into Perfect Photo Suite 9
• In Suite 9
  • Duplicate the layer
  • Send the photo to Perfect Enhance. Stylize with the Auto Levels & Colors preset.
  • Send the photo to Perfect Effects. Stylize with the Pastel Bliss preset. 
  • Send the photo to Perfect Black & White. Stylize with the Bogart Neutral preset.
  • Add the Old Parchment texture in Layers with a simple gradient mask
• Save the image back to Aperture

The preset choices aren't important. What's important is that the experiment creates a few layers, has a layer mask, and is a good representation of a typical editing session. In all honesty, the resulting images weren't that pleasing (which is why you don't see them here).

The PSD file sizes show that Smart Layers produces a file size about 15% smaller than simple layers.

I ran the TIFF experiment mainly as an additional data point. Perfect Photo Suite will round trip from Aperture as a TIFF. However, the resulting image is flattened on the return and no layering information is maintained. Although the TIFF format supports layers, there's no requirement to use them... and that's certainly the case with Suite 9. I would not be surprised if a layered TIFF is roughly the same size as a PSD with simple layers.

AN ASIDE

I also got curious if flattened PSD files would be roughly equivalent to TIFF files.

The results surprised me. Flattened PSD files are twice as large as their TIFF counterparts. If you're going to work with flat images and you are sensitive to storage space, use TIFF. Although, I honestly don't understand why you'd choose to work in a non-layered format in Suite 9. Doing so defeats a lot of the value gained with a layered workflow.