TIFF vs PSD...again!

[agillanders]

Folks,

I know from searching back that this has had discussion in here before but it was a few year ago. It appears from research here and on the Adobe forums that it is hard to get a definitive answer. The thread at http://www.luminous-landscape.com/forum/lofiversion/index.php/t17170.html suggests that PSD is really a legacy format, but others comment on compatibility with other tools in CS (none of which I use right now but might in the future).

So I get to some very basic questions.

• Is it really true that TIFF retains everything that PSD does; especially with respect to non-destructive editing?
• Just to emphasize this point...will TIFF even handle the new layer types from CS3/4 and so on (e.g. multi-layer smart objects that might include nested multi-layer smart objects)?
• If so why does PSD persist as the percieved native format of choice?
• If layer info is properly persisted in TIFF then if I need PSD in the future for InDesign or whatever, can't I simply convert at that point?
• What are the metadata implications? I've seen vague references to differences but can't find specifics.
• Does anyone know if Adobe is going in a particular direction with these formats...since they own them both?

Finally...if TIFF is the way to go...uncompressed vs LZW vs ZIP?

Thanks in advance

Alistair

[peterkrogh]

Alistair,
First, you're way over-thinking this.  You're very safe with either.

Second, It's my understanding that anything PSD can save in a file will also be saved in TIFF. I think the biggest difference has to do with PSD's ability to be saved without previews, which can make the file smaller at the expense of compatibility.

Yes you can convert between the two iif you happen to need a PSD in the future.

As to why the preference for PSD persists, probably the same reason everyone says "300DPI TIFFs for delivery".  Some urban legends take forever to die.
Peter

[agillanders]

Over thinking? Me?

Ummm...mea culpa. When I get into researching something I usually try and go somewhat beyond the normal boundary...just so I know I've actually found it.

In this case I am making several changes almost all thanks to you...dng being one, tiff now being another, and my folder structures, naming conventions and some of my metadata practices! For me it is very non-trivial and worth the investment now to reduce the need for more changes down the road (although I feel sure something will come up:-)).

My copy of your book is falling apart BTW...I'll maybe have to get another for longer term reference! Sits on "most used" my shelf alongside Ben Willmore's Studio Techniques.

Thanks again for your patience and support (and Beardy too!:-))

Alistair

[rogerhoward]

Wow, ok a lot of questions here. I'll take them one by one.

• Yes, a "layered TIFF" from Photoshop supports the exact same features as a PSD, by virtue of it encapsulating the layered data structures of a PSD in TIFF... in other words, it's like a PSD stuffed into a TIFF. Same features, same everything; different file format wrapper, bringing some additional features like different types of compression.
• Yes, see above - if you don't believe, why not test it? It'd take you a few moments at most to satisfy yourself. Create a file with every PS feature you can think of; save it as a PSD. Now, Save As as a layered TIFF. Close the TIFF; reopen it. All features retained?
• Many reasons. Perception (how many times have I heard "TIFF is for print, JPEG is for Web, PSD is for layers"?), momentum (or inertia? depends on perspective), performance (PSD is optimized in part for editing performance, whereas layered TIFFs, particularly with certain compression options, can be a dog), conventional wisdom, habit, defaults, and neglible or unknown/undefined benefits for some (and demonstrable benefits for others).
• Yes... or, depending on use, you could just use the TIFF with InDesign.
• TIFF is more broadly supported, and more flexible, with respect to metadata and third-party tools, than PSD...
• You'd have to ask them, and I suspect they'd not say much other than things seem to be working out fine with both right now... they've not shown any obvious desire to change either - in fact, they extended PSD ("Large File Format" or PSB) a few years back, while they have yet to show any commitment to supporting BigTIFF for larger TIFFs. My guess is, things will stay as-is for now - why would they change? Just because TIFF is an "open" format doesn't mean all the data stored in a TIFF has to be openly documented - so they can have their "open standard" cake and eat it (proprietary extensions) too.

If you're asking about Layered TIFF compression, I'd recommend ZIP for image data in 16 bit files and LZW in 8 bit files. If you're going uncompressed, why not use PSD?

[agillanders]

Roger.

THANK YOU!

That's the clearest explanation I have found anywhere!

Oh...and yes I did test it...including launching the TIFF edit from within LR2.3. All the information was indeed intact unless I had made further adjustments in LR when there were a couple of gotcha's – but that is not unreasonable in the circumstances! :-)

The test file was a 16 bit image with mulitiple layers and nested multi-layered 16 bit smart objects with smart filters and layer properties against the smart objects at both levels.

For reference in this test on the complex image with additional LR adjustments on top:

• Edit a copy with LR adjustments worked OK but it was only the flattened image.
• Edit a copy failed - it would not open. But this MAY be a LR2.3 vs CS3 thing...I haven't put CS4 on this laptop yet so it's ACR4.6 rather than 5.3.
• Edit original worked as advertised with all thelayers intact but did go through ACR first which surprised me and messed with the colors a bit.

And thanks to your explanation the file sizes even make sense:

• PSD with compatibility turned off ~170MB
• PSD with max compatibility AND TIFF with ZIP compression ~210MB (so close to the same that the difference is not worth worrying about)
• Uncompressed TIFF ~270MB

I'm convinced!:-)

And now I finally understand the key concepts I feel comfortable with making a decision...layered TIFFs for the archive (long term files) and PSD without max compatibility for work in progress (short term files) it is!!

Thanks again.

Alistair

[rogerhoward]

I've not tested the roundtrip through ACR or Lightroom, you've got me there - my workflow never encounters that... but purely within the Photoshop environment, layered TIFFs will preserve all the same data as a layered PSD from the same source.

Glad I could help,

Roger Howard