Photoshop .psd and .psb compression

[Martimkasper9045834]

Hello Everybody,

can somebody explain me how the compression of .psd and .psb files works (which can be deactivated), it brings a lot of benefits without and within using it.
So I want to know how it works, if it is lossless, and when it is lossless how it can compress a file that good. Sadly the german helpdesk wasn't helpfull at all.

And is it possible to make a action which can be used afterwards to save Files with compression when the work is finished. The plan behind this action is to work with uncompressed files, which can be safed much faster and then compressed afterwards via. a droplet. This would safe me a lot of time.

thanks in adavance!
Max

[c.pfaffenbichler]

The compression is lossless.

As for the Action I am not sure it would be a good idea.

Changing Preferences does apparently record in Actions but if the Action should hit a bump before finishing you might be left with unnoticed but unwanted Preferences settings.

Scripting might provide a better, though still not necessarily fool-proof alternative.

[Martimkasper9045834]

c.pfaffenbichler​

do you know which compression method is used for both(.psd & .psb)? I can't find anything about it which is approved by adobe.

I'm not familiar with scripting, I'll try it with a droplet first, if it fails I maybe give scripting a try. Thanks for the advice!

@Test Screen Name 

I've tried it and there is a big difference for me as a professional, if I would use no compression for the Data I'm gona work with, it would save me very valuable time during the workday.

I compared two .psb documents, one uncompressed, the other one compressed. I've used 16bit ProPhoto RGB Pictures with several layers, groups and paths, the compressed one has 542Mb and the uncompressed document has 1.81Gb which doesn't matter on a single document but it becomes a really big difference when  you need to read or write a hundreds of documents in terms of writing / reading time and disk space.

to open:
w/o compression 2,51sec.

w/i  compression 6,33sec.

saving:
w/o compression 6:69sec.
w/i  compression 28,76sec.

do you know which compression method is used now and how it works?

JJMack​
thanks for the explanation! I haven't thought about this fact yet, but I'm using SSD - The Harddisk is used for the Backup an I'll never work on that partition due to perfomance issues.

The plan is to use to use the scripts or actions when the work is finished. During the working process I'll need to open and close the data several times, waiting for corrections from my client and so on.. but when the work is finished I'll really benefit from smaller data which will be written on my NAS for my long time Backup, most of the time I'll never touch that Data again, so I don't need it to be fast openable, so it becomes a big benefit to have small but complete data, this would save me a lot of money I don't need to spend Hardrives every year.

[JJMack]

I use external USB 3 Hard disk for storing my files.  With the cost of 4TB drives being under $200 how much new data do you collect each year in large files. That compression will save you lots money.  Compression only save disk space on large files. Small file consume more disk space then their size because of the way disk space is allocated.

[Martimkasper9045834]

JJMack​

I'm using a 4 Bay NAS with WD RED Pro Harddrives which are a bit expensive, I'm using two clusters, both mirrored, they get backuped on another four Harddrives via a Sata Dock so I have a second backup mirrored at a diffrent location, this makes it a bit expensiv.

My files are most of the time bigger than 3Gb, which I think would double I dissable the compression which I'm using by default.
Discovering this feature really scared me, because I can't find the trick behind the magic. I really want to know how it works and if it is definatley lossless.

[c.pfaffenbichler · Accepted solution]

As per Test Screen Name’s

The original PSD compression was run-length.

it’s run length.

File formats in Adobe Photoshop

Run-length encoding - Wikipedia

[Martimkasper9045834]

c.pfaffenbichler​ thank you very much for solving the mystery!

[c.pfaffenbichler]

Well, actually it was Test Screen Name who did it.

[Martimkasper9045834]

Ahh than thanks to Test Screen Name​, I was irritated because he said "was".. I'll let your post liked as answered because of the links which can help if somebody wants to dig deeper.

[Test Screen Name]

Have you compared the save speed without and with compression? I would expect the compressed file to save faster, but I haven’t tested it.

[JJMack]

The Compression/Decompression used does not lose data. I do not know which method or methods Adobe use. Data compression has performance implications.  Compression/Decompression add procession path so it increases processing path length.  However Compression Data shorten Disk read time.  Disk write time his somewhat hidden by buffering and delayed writing.  However SSD shorten disk read time for there is no seek head latency and SSD data transfer rate is high.   So if you are using  SSD most of the Time you may see better performance not using data compression to reduce processing time.  If you are using disk and are using large files you may  see better performance using data compression by reducing file read time.

So I think is more a configuration Performance issue not something you would want scripts and actions to play with

[Test Screen Name]

The original PSD compression was run-length. Not very effective, but very low on CPU requirements.

[D Fosse]

FWIW, I've turned off the compression permanently. It has a huge impact on save/open times for big files - especially for layered files where the compression is excruciatingly slow.  A file that used to save in a minute now only takes a couple of seconds.

The downside is of course file size, but I'm not concerned with that. When the disks start to fill up, I get bigger ones (with the added advantage that disks never grow to old age and potential failure).

[Martimkasper9045834]

Hey D Fosse   

I would copy that, but most of my documents have a filesize of around 5Gb compressed, this would end up in a mess so it would become really handy to use a script during the night before making a backup and benefit from both compressed and uncompressed data. I don't need my backup to be that fast but I don't care about big data on my workstation.

And on the other hand I really want to know what happends with my data if I enable compression, it scares me a bit to trust in that process while I don't know anything about this process yet.