Luminous Landscape Forum

Raw & Post Processing, Printing => Adobe Lightroom Q&A => Topic started by: Pindy on December 15, 2013, 01:10:35 pm

Title: Do Smart Previews make sense for JPEGs?
Post by: Pindy on December 15, 2013, 01:10:35 pm
I've essentially banned RAW in two of my cameras (X100 and X100s) and I'm only shooting blasphemous JPEGs with them. I haven't spent much time with LR's smart previews, but I'm wondering if they are of any use with JPEG originals? Or would the JPEGs take up less or equal space just keeping them on my laptop internal, rendering smart previews meaningless for anything already compressed?
Title: Re: Do Smart Previews make sense for JPEGs?
Post by: john beardsworth on December 15, 2013, 04:16:06 pm
Smart previews' main value is enabling you to work on images when you don't have the originals available, so I can put on the laptop my entire catalogue with smart previews and then edit images while on the road.

If you're trying to do something like that, you could keep the JPEG originals on an external drive and only have the catalogue with its smart previews on the laptop. Assume they take around 7-8% of the space of the originals (though that rule of thumb is based on raw files and not tested with JPEGs).
Title: Re: Do Smart Previews make sense for JPEGs?
Post by: Pindy on December 15, 2013, 08:46:05 pm
Quote
Assume they take around 7-8% of the space of the originals (though that rule of thumb is based on raw files and not tested with JPEGs).

Right—the testing on JPEGs is what I'm angling for. It's clear that there will be a significant difference, but I'm not sure how to test it myself. I suppose I could export one JPEG file as DMG/lossless/2540 long side?
Title: Re: Do Smart Previews make sense for JPEGs?
Post by: Pindy on December 15, 2013, 09:06:13 pm
This is fairly unscientific: I took a RAF file, converted it to JPEG @ 100% and 90%, then also exported a lossy DMG @ 2540:

RAF — 33.5MB
JPEG from RAF @ 100% — 6MB
JPEG from RAF @ 90% — 3.2MB
dmg/lossy from RAF — 1.6MB

Title: Re: Do Smart Previews make sense for JPEGs?
Post by: john beardsworth on December 16, 2013, 04:24:29 am
To be sure, why not just create a small test catalogue with some JPEGs and the smart previews? You can then look at the size of the smart previews folder and be sure the smart previews have the true size and compression. Obviously the space saving will be less than with raw files.

John
Title: Re: Do Smart Previews make sense for JPEGs?
Post by: luxborealis on December 31, 2013, 05:22:19 pm
I wouldn't bother with Smart Previews if you are determined to only shoot jpegs. Besides a slight savings in space (and hard drive space is cheap), it's a JPEG of a JPEG, so no other advantages. I can't imagine there is even a time saver as LR doesn't load originals anyway.