You might be very surprised at my answer in today’s edition of the Ask Tim Grey eNewsletter. It relates to the relative merits of saving images in the Photoshop PSD versus TIFF file formats.
A reader indicated that a Photoshop instructor had told him (rather emphatically) that they only save images that are worked on in Photoshop (via Lightroom in this case) as TIFF images, never as PSD images. The reader wanted to know what I thought about this.
Most significantly, perhaps, I let my Ask Tim Grey readers know that conventional wisdom is sometimes wrong. In this case, potentially very wrong.
You see, conventional wisdom seems to believe that since the options when saving in the TIFF file format include a compression setting, and the PSD file format does not, that the TIFF file will always be smaller. It won’t. In fact, often the TIFF file will be larger. Much larger. Worse yet, in many cases a TIFF image with LZW compression applied will be larger than the same TIFF image without compression applied. Yes, compression for TIFF images can actually make the file larger!
Generally speaking (though there are many exceptions), when working with layered photographic images in Photoshop you’ll get the smallest file sizes with a PSD file with the Maximize Compatibility option turned off. However, Lightroom can’t import PSD images unless the Maximize Compatibility option is turned on, so for many photographers this option isn’t useful. In my experience, most photographers who utilize the TIFF file format either don’t use compression or use the LZW compression option. In both cases, for many (if not most) photographic images, the TIFF image will be larger than a Photoshop PSD, even with Maximize Compatibility turned on for that PSD. That’s in part because contrary to what most photographers seem to assume, PSD files include lossless compression automatically.
To be fair, when saving a photographic image with layers you can get a smaller file size with TIFF in most cases compared to a Photoshop PSD. However, the only way to help ensure that file size will be smaller is to save the TIFF with both the image compression and layer compression options set to ZIP (ignoring the option for lossy JPEG compression). Those are not the defaults, and they are not the settings most photographers seem to choose in my experience. However, even with these options, the TIFF image will only be slightly smaller than the PSD with Maximize Compatibility turned on.
My primary reason for favoring the Photoshop PSD file format over the TIFF file format for my layer-based images is purely pragmatic. TIFF files with layers weren’t supported in earlier versions of Photoshop, so I always knew that my PSD files were my layered “master” images and my TIFF files were flattened derivative images. While it is now possible to save files with layers in the TIFF format, I keep using PSD so that I know at a glance which images are my master images and which are derivatives, and I can easily filter them accordingly. Quite often, I’m also benefiting with a smaller file size as well.
Did you have any idea that a TIFF file with compression applied could be larger than a TIFF without compression? And that a PSD file actually does include lossless compression that can make the files smaller than TIFF images in many cases? Feel free to share your experience in the comments below.