Tiff vs PSD

Started Oct 12, 2011 | Discussions thread
Jeff Schewe Regular Member • Posts: 425
Re: Tiff vs PSD

JerryG1 wrote:

I did a small experiment and now am sorely tempted to switch over to PSD for archiving. But, I remember no less an authority than Jeff Schewe espousing the awfulness of doing that a couple of years ago.

Just to be clear, there's PSD's that are saved with and without the composite file (Backwards Compatibility). Saving without the composite file will result in a smaller file size for PSD vs TIFF (particularly as 8-bit layered files).

However, saving without the composite limits the ability to use that PSD in other applications-even Lightroom won't import them.

The smallest layered 16 bit files with broad compatibility are TIFF files with Zip compression (which is lossless). Yes, it takes a bit longer to save and open Zip compressed TIFFs...

I still do not like the proprietary nature of the PSD file format which is essentially undocumented (unless you apply for the super secret PSD file format SDK from Adobe). Essentially everything you can save in a PSD file you can save in a TIFF file (with the modest exception of crop data).

But...Camera Raw can't open PSDs at all (it can open flattened TIFFs and JPEGs) and Lightroom can only open PSDs that have been saved with the Backwards Compatibility option which makes the files nearly as large as TIFFs with zip compression.

PSD uses a run length encoding–which for layered 8-bits is pretty good file size savings (less good with 16-bit). It's lossless.

But the TIFF file format is publicly documented and widely supported. It's not "proprietary" in any way. PSD "used to be the native file format of Photoshop, but that all changed whan Adobe started the Creative Suite. Now, Photoshop's only true native file format is PSB (needed for really large documents but useful even for smaller documents).

So, if file size and only Photoshop (or Creative Suite) compatibility is the ONLY criteria...there's nothing specifically wrong with PSD as a file format–other than the reasons listed above.

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Jeff Schewe

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