Friday, July 22, 2011

Photoshop Tip: How to Reduce Size of PSD Files

compress-psdPSD, Photoshop's native file format, is an impressive one because it stores an image while preserving practically every imaging options available in Photoshop. These include layers with masks, color spaces, ICC profiles, transparency, text, alpha channels, clipping paths, and more. This allows you to save your work and return back at any time to make changes or continue working on it from where you left.

That’s a lot of information to save, and this makes PSD files quite large in size. PSD files of complex layouts with sizes up to hundreds of megabytes are not unheard of.

Here is a nifty trick I learned years ago in a magazine that lets you reduce the size of PSD files by as much as 40% and even more, without compression. How? Simple, just add a new layer on the top, color it white and save it. Instant weight loss.

photoshop-white-layer

The downside of this is that you lose the thumbnail preview in file explorers and other software. But no loss in image quality occurs or editing features lost.

I couldn’t get a satisfactory answer as to why this happens. PSD is Adobe’s proprietary format and it’s specification is a closely guarded secret. Perhaps, nobody outside Adobe has any clue of how PSD saves file information. But the trick works.

I tried this on a number of PSD files, and these are the results.

PSD File Original size Size after addition of white layer Percentage saved
Sample 1 54,266,801 bytes (51.7 MB) 31,851,238 bytes (30.3 MB) 41.3%
Sample 2 41,981,239 bytes (40.0 MB) 25,006,786 bytes (23.8 MB) 40.4%
Sample 3 6,414,209 bytes (6.11 MB) 5,099,130 bytes (4.86 MB) 20.5%
Sample 4 3,893,914 bytes (3.71 MB) 2,857,056 bytes (2.72 MB) 26.6%

You can further reduce the file size by archiving it. The 30.3 MB file (sample 1) became 14.5 MB when compressed and packed into RAR. The 4.86 MB file (sample 2) shrunk to mere 688 KB.

Keeping all files archived is impractical, particularly if you access them often. But if you are saving them for safe keeping or uploading online, then why not?

1 comment:

  1. unfortunately you don't get much of a savings with a lot of smart objects in the file...663 megs went down to 660 :-( although rar'ing still brings it down regardless. 660 megs went to 418

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