Today’s Question: You suggested that the Maximize Compatibility for Photoshop PSD files wasn’t required to open an older PSD file with the latest version of Photoshop. If that’s the case, is there any reason to actually use Maximize Compatibility?
Tim’s Quick Answer: The Maximize Compatibility option for Photoshop PSD (and PSB) files is not generally critical for photographers using a workflow that revolves around Photoshop. If you are using (or planning to use) Lightroom, however, you will want to enable the Maximize Compatibility feature. The Maximize Compatibility option also enables you to preview PSD files with other software applications, and ensures that an image will maintain the same appearance even if opened with a significantly different version of Photoshop than it was created with.
More Detail: As you are probably already aware, in Photoshop you can create images with a variety of different image and adjustment layers. To retain layers in an image, you need to save it as either a TIFF or Photoshop PSD file. With the Photoshop PSD file format you have the option to enable a “Maximize Compatibility” feature. Note that enabling the Maximize Compatibility option will double the base file size for the image, so you may not want to use it unless you absolutely need it in your workflow.
On the File Handling tab of the Preferences dialog in Photoshop you’ll find an option for maximizing compatibility for PSD (and PSB) files. You can always enable the Maximize Compatibility feature, never enable it, or have Photoshop ask you whether you want this option enabled each time you save a Photoshop PSD file.
When you enable the Maximize Compatibility feature, you are essentially saving a flattened copy of the image as an additional layer, beyond the image and adjustment layers you would otherwise see on the Layers panel. This serves two basic features.
First, with this flattened composite layer as part of the file, other software applications can render proper previews of the image. Note that Lightroom does require that Maximize Compatibility be turned on in order to import these files into the catalog.
Second, the Maximize Compatibility option helps ensure an image can retain the same appearance even if it is opened with a different version of Photoshop than it was created with. For example, the algorithms for some of the adjustment layers have been changed from time to time. If you open a PSD image from an older version of Photoshop with a version that uses different algorithms, the appearance of the image would be altered. With Maximize Compatibility enabled, you can essentially open a flattened version of the image that looks accurate, or a layered version that may not be accurate.
So, Lightroom users most certainly need to enable Maximize Compatibility for all PSD files they will manage within Lightroom. Photographers who won’t be using Lightroom generally don’t need to enable this option.