I've noticed, as have others before me, that exported HIGH quality JPG files are much smaller than exported MAX quality JPG files. Can someone explain the differences? I've done some tests and to naked eye (mine) the images don't look that different on screen (Retina). But the MAX exports are often almost twice the size of the HIGH exports.
What's going on with this?
MacBook Pro (Retina, 13-inch,Early 2015), OS X El Capitan (10.11), null
Obviously, the difference will only be apparent at higher magnifications.
Export whatever is good enough for your project, but keep the original file at its original resolution. You never know what quality you might need in the future.
What is going on? Simple. The higher the quality the lower the compression therefore the larger the file - Lower quality uses higher compression and therefore has smaller files, higher quality uses less compressing and therefore has larger files
LN
Actually, I doubt this, because: often the MAX export file is LARGER than the original file in Photos. For example, I have old 550 KB photos that are suddenly 1.5 MB photos when exported. I wonder if it's possible that detail lost in the original compression (down to 550 KB) can be regained by a recompression at 1.5 GB?
Appreciate your help, but please see my reply above. This is what's troubling me--that the exported version is LARGER than the version in Photos that's being exported. Thanks again--
You are overthinking this - it is very simple
Lower quality uses higher compression and therefore has smaller files, higher quality uses less compressing and therefore has larger files
Nothing is adding information to the original - you are simply taking what you have and compressing it different amounts - no JPEG is going to be as good as the original - to do that export a TIFF - but the less compressing you use on the export the closer you stay to the original - every time your recompress the data you lose something -- compress less and you lose less - compress more and you lose more
It is very simple - do not make it complicated because it is not
LN
Thanks again, but you may be missing my point. The ORIGINALS in this case were JPG files, shot and saved as such and brought into Photos (probably via iPhotos) as such. Thus I wonder why the EXPORTED new JPG files are larger than the original JPGs. I get the idea that lower compression means higher quality, generally speaking, but simply COPYING (as export) would produce LESS degradation that re-compression, unless I'm very much mistaken, which is always possible.
Anyway, thanks for sticking with me on this issue.
Exporting is not simply copying - it is creating a new file with new compression and the amount of compression you apply determines the size of the file - when you export form Photos you start with the original and apply any and all changes made adn create a new file
If you export the unmodified original then you simply copy the file exactly as imorted
LN
Yep, got that. But . . . I hope this is not to aggravating. My point is that the photos in question are already JPGs in Photos and some of them have been edited in Photos, and I want to keep the edits on the few hundred files that have been edited. Oh, wait!
LIGHTBULB!
The edited files aren't actually edited files, they are original files with a list of edits to be made when output. So the edited files CANNOT be "copied" anywhere. They must be "made" from the original JPG files and the list of edits! So, to to get them out you MUSt make a NEW JPG file that, by definition, is re-compressed (i.e. that's what a JPG file is)! If you want the full file w/o new compression you must export as TIF or PNG (assuming you can).
This is what you've been trying to tell me all along? I think i've got it. I was confused when looking at an edited photo in Photos I saw all the edits in place and forgot that the edits were "non-destructive" and so there was NO EDITED FILE ALREADY AS A JPG on the drive.
Double duh. Got it now & thanks for your help.
good
And the reason Photos handles it this way is to reduce loss - with a traditional editor like PhotoShop you make edits and save the file and the new file is compressed losing a bit - you do it again and you lose a bit more - if you edit enough you lose enough to make a noticible reduction in quality - with Photos no matter how many times you eidt you lose nothing - when you export all of the edits are applied adn then the photos is compressed adn saved giving you a single compression loss only when you actually export
LN
Thanks for helping with this and for the explanation, which makes perfect sense. I'll trouble you with one more question here:
When I exported my 30K pictures I exported NOT the originals, but new versions (to save the Photos edits I'd made in a couple hundred pix). I exported as "full size" and "Max" quality JPG.
I wonder if exporting as "originals" would SIGNIFICANTLY improve the quality of the pictures (since it's a simple "copy").
I'd prefer to keep the edited versions IF the single export to the new JPGs hasn't significantly reduced the quality of the pictures, both edited and unedited.
No - the loss in a single high quality compression is very small - it only becomes significant when done many times or when you do a lot of compression (low quality vs high quality)
LN
Difference Export JPG High or JPG Max?
