PSE 6 File size when saving JPG/JPEG at maximum quality

[bschacht]

hi, when i save a file as JPEG in editor with a quality of 12, i notice that the file size actually increases relative to where it started before as a JPEG. This without any actual editing. For this reason, i usually save at quality 11, but other posts indicate this would somehow be leaving some quality on the table. On the other hand, it seems weird that PSE would increase the file size without introducing bad artifacts.

Net/Net: what is the best quality to save at (for JPEG) and what am i giving up (or gaining) by saving as Quality 11 instead of Quality 12.
thanks

[Michel B]

I never save more than 10. You can either test it yourself or have a look at the numerous posts on the Web on this matter. Many printing services strongly advise using 8-10. Using 12 would be sensible for saving an edited raw file. While it is advisable to use the max compression camera setting if you shoot jpeg, the final save from Photoshop for printing gains nothing visible by doing so.
The fact that the file size has increased does not mean your image has gained in significant detail, but my guess is it has recorded added artifacts from the first save. (Probably hardly visible even at 100% magnification).

[dj_paige]

JPG is a compression algorithm. If you have a file that is saved at, lets say 10, and then you go ahead and save it as 12, then 12 does less compression than 10, so the file will be larger.

The choice is yours, you can select higher quality (less compression) at the expense of larger files, or you can select lower quality (higher compression) and smaller files.

If you are looking at files on your screen or printing 4x6, I don't think most human eyes can see the difference between JPG 8 and JPG 12. If you are printing larger sizes, or looking at the photo at 100% magnification, then the differences might be obvious (and might not be obvious).