RAW vs JPEG In Lightroom (Freddie Returns)
(from Kevin Swan’s post on OSP)
OK. Someone had to do this…
I’ll stick the executive summary at the top… 
Rating speed in LR beta 4.1, it appears the code has been optimized to the point where there is no significant advantage to running raw over JPEG. In the case of batch-applying presets, JPEG actually proved to be slightly faster. In managing files (importing, rendering 1:1 previews, exporting) raw was slightly faster. If someone else wants to perform these tests on a slower machine, we may see a greater discrepancy in the numbers, but my Mac Pro muscled through these tests without any lag.
This means the choice for raw vs JPEG should come down to quality. The thing to keep in mind is that raw files are 16 bit. What that means is you get 65,000 levels of color for each channel (r/g/b), which will result in more accurate colors and especially shadows. JPEGs are in 8 bit, which means only 256 levels of color for each chanel. Granted, most people wouldn’t be able to quickly spot the difference between a raw and JPEG photo, but you can if you look.
Another major advantage raw has over JPEG is non-destructive image storage and processing. JPEGs are smaller because they are compressed. Compression means permanently eliminating data from the image to make it smaller. Every time you save a JPEG, the quality will degrade.
Lastly, raw will give you a significantly wider range of flexibility in post production. You can stretch a raw file much further in regard to exposure, white balance, saturation, etc. I’m not saying you can’t do it with JPEGs, but you will see the tones start to break apart, noise problems, etc. if you push it past a pretty limited range. If you don’t have a problem shooting a pretty good exposure to start with, this will be less of an issue–although, if you want to really super-saturate, or play with some more special effects, you’ll be more limited in the JPEG format.
THE TEST:
I just took one of my raw files and created a high-res JPEG out of it. I then put the JPEG in one directory and the raw in another. I duplicated each one 91 times, so there are 92 copies of each image. The 8.2mp raw file was 8MB, the JPEG was 3.6. It is a Adobe RGB image.
I went to LR and did an import, referencing the files in their original locations (since this is how I normally work). I did not apply any development settings. Lightroom was in window mode, libarry, small preview with both side tabs open. I showed most of 48 previews. Here’s what I got:
Rendering standard preview option selected:
Importing 92 raw files: 55 seconds from click until the task bar said “complete.”
Importing 92 JPEG files: 57 seconds from click until the task bar said “complete.”
Using embedded previews: (best time out of 3 tries)
Importing 92 raw files: 9 seconds from click until the task bar said “complete.”
Importing 92 JPEG files: 9 seconds from click until the task bar said “complete.”
Note: since LR isn’t set to do any type of processing on JPEGs (I don’t think), once they were imported, that was all LR did with them. The raw files took a little more time to do the default LR raw adjustment–but I don’t think you can disable this.
Next I wanted to see how doing any type of edit to the images would take. I used default Lightroom presets, so you could all try it yourself… I made the thumbnails SX and resized the screen until all 92 images were on, so I could see how long it took to update the thumbnails.
Applying “antique greyscale” to all images:
raw: 17 seconds to update all thumbnails
jpeg: 9 seconds to update all thumbnails
(Note, on the JPEG, the first 3 times it would stop updating after getting through most of the thumbnails, leaving about 8 un-updated–the little spinning indicator just stuck. If I moused over an un-updated thumb, it updated it immediately, so the process was complete, just didn’t show up in the thumbnail. This appears to be an LR bug. I tried deleting and re-importing the images, then doing the preset again with the same results. Finally, on the 4th try, I got it to go through.)
Because of the cache in LR, I had to try a different preset to run the next test:
Direct positive:
raw: 10 seconds
jpeg: 8 seconds
Rendering 1:1 previews (something I HIGHLY recommend to speed up Lightroom’s general performance:
jpeg: 2:35
raw: 2:14
I tried playing with white-balance adjustments, but it happened so fast for all images on my Mac Pro that it was hardly measurable. It looks like about 5 seconds for raw to go from default to fluorescent and about 3 seconds for JPEG.
Exporting all 92 images at 90 (out of 100) quality JPEGs (if you’re making edits in LR, you will have to export your JPEGs out again as JPEGs, which means re-saving with lossy compression). You will lose some image quality in this process, though it will not likely be noticeable to your client.)
JPEG: 2:47
RAW: 2:36