How does the usual jpeg 0-100 quality settings translate into Photoshop's 0-12 quality setting?

Question

JPEG encoders usually use a quality setting of 0-100, whereas Adobe photo software uses a 0-12 setting. Does anyone know how to convert between these? (I am actually not clear on whether the 0-100 quality setting simply became common since the independent JPEG groups encoder did so, or if such a scheme is part of the JPEG standard itself). I looked around to see if someone else asked this, thinking someone already would have. There were related questions that I found, but not this one. Please correct me if I'm wrong and I'll delete my question.

Answer 1

If you are using Photoshop CC, try using Save for web. It's a legacy command and to access it select:

File->Export->Save for Web

It will allow you to select the file compression you want from the right hand side of the dialog box and show you a preview of what the affect is. Note that you can select Low, Medium, High etc. from the drop down or select 0-100 with the slider. This should give you a rough estimate how they correlate.

Answer 2

JPEG compression settings differ in that it is referring to how much you compress something. The more you compress it, the more it will drop colors and create artifacts. Photoshop quality settings on the other hand are exactly opposite of this. A 12 means that you are setting the amount of compression to the least possible amount. (JPEG's compress no matter what, but is still has a value of high compression to low compression)