confused about quality settings for jpg

[Christian2419640508y8]

Thank you for adding me! I'm really confused, maybe someone here can help. I was using Affinity Photo the past two years and switched back to Photoshop. For starters when exporting Jpg manually it keeps defaulting to 6 instead of 7, I have to keep changing it, any way to fix it so it stays on 7 by defualt? quick export seems to do fine on 7, which I guess is the highest quality now. But when I do script batches with image processor of PSD to JPG, if I set quality on 7 the files are tiny, if I set it to 12 which use to be the highest quality, they are larger and seem better quality? which confuses me because I thought 7 was the highest now?

[Derek Cross]

Welcome to the forum

There are several ways of Saving (and there's also Save a Copy) in Photoshop and there's also Exporting images. 

Maybe to explain why you choose the different methods and the various digital formats have a look at this excellent YouTube tutorial:

https://www.youtube.com/watch?v=5CS_oieQL7c&t=46s

[TheDigitalDog]

First see: https://www.adobe.com/creativecloud/file-types/image/raster/jpeg-file.html

As for Photoshop's scale, 1-7, etc this change was well explained by an Adobe employee (BrettN):

"A while back, we changed the default method of using Export As to working with the new UXP-based method. The older CEP-based method (which used to be the default) is now activated by enabling the "Use Legacy" option in Preferences.
 
One of the big differneces between the two methods is the Quality setting for JPG files. In CEP, it used a API which allowed for a 1-100% quality scale, which is similar to the one used by Save For Web. UXP has an API which only allows for a scale of 1-7, which is similar to what is used in Save As. This scale is equivalent to approximately 15-20% jumps on the old scale. So 7 on the new scale is the same as 100% on the old, 6 is around 80%, and so on. Unfortunately, this is not something we can readily change, we are reliant on another piece of technology for this feature and are currently restrained by its limitations. 
 
The 1-7 scale is a more recent UI change, from the old descriptors scale (Poor, Good, Great, etc). We only changed these labels to numbers, to make it easier to understand. We didn't change anything at all about the underlying JPG compression: 7 is exactly the same as Great and so on. 
 
In your screen shots, we see exactly what we expect to see: 7 (from a scale of 1-7) in the new UXP settings ("Legacy" setting is off) is high quality. But 7 using (from a scale of 1-100) in the old CEP settings (Legacy is on) is low quality". 

[Christian2419640508y8]

For some reason in scripts / image processor it seems to still go by 1-12 it seems?

[D Fosse]

Image Processor uses the Save As jpeg algorithm, which is different from the Export algorithm.

[J453]

See also this thread:

https://community.adobe.com/t5/photoshop-ecosystem-bugs/p-inconsistence-jpeg-quality-with-1-7-slider...