Determining the ideal JPEG quality setting in both Photoshop and Lightroom can be challenging, because we often see two different values to choose from. Photoshop gives us compression levels from 0 to 12 when saving JPEG images through the “Save” or “Save As” dialog, while Lightroom only allows us to input a percentage. While percentages are easier to understand than numbers from 0 to 12, as we relate to 100% being the “best image quality” easier, Adobe also created a confusion as to what number represents what percentage, since the ranges of numbers are not provided in any of the help documents. The truth is, the percentages we see in Lightroom do not really scale from real 0 to 100 in single digits. Adobe simply mapped the 0 to 12 scale to the percentage scale. This ultimately means that changing from one number to another, like from 85% to 90% might make no difference whatsoever in compression or image size, while changing from 84% to 85% would make a big difference.
Below are the different screens we are used to seeing. First, here is the screen that shows up when you click “Save” or “Save As” and choose JPEG in Photoshop:
As you can see, the values you can choose from a represented in a number scale from 0 to 12. And here is the Lightroom export screen:
Here we see the representation of the JPEG compression scale from 0% to 100%.
Now let’s take a quick look at the table below, where the 0-12 values from Photoshop are mapped to percentages:
|PS JPEG Compression #||PS Scale Name||Equivalent in %||Sample File Size||Space Saving in % *|
|* Space Savings represented relative to the largest file size at 100% Quality (27.3 MB) and full resolution (captured with a 20 MP camera)|
So what does this mean? It basically means that some numbers don’t matter at all, while others do quite a bit when we use the percentage scale. Choosing say 80% quality, is the same thing as choosing 77% or 84%. Until you get to 85%, nothing really changes. The same goes for 90% – it is no different than picking 85% quality!
Photoshop’s Save for Web
In my original article I wrongly stated that the “Save for Web” feature of Photoshop worked similarly as the percentage field in Lightroom, which is wrong (thanks to Aaron Shepard for catching that!). In fact, the “Save for Web” feature of Photoshop works differently, as it uses a different compression algorithm compared to the 0-12 numbers or the percentage in Lightroom. Here, every number from 0 to 100 matters and the file size can vary in size considerably.
Here is the “Save for Web” screen in Photoshop:
What’s important to note about this screen, is that it is optimized for smaller resolution files that are meant to be published online. As you can see, there are more ways to customize the final JPEG and you can decide whether you want to preserve the EXIF data (Metadata field) or strip it out completely, along with the Color Profile.
Best JPEG Compression Level
If you have been using 12 or 100% quality when exporting JPEG images all the time, you probably ended up with a lot of bloated images that are huge in size for no good reason. The thing is, you are defeating the purpose of the JPEG format when going with 100% all the time, because you are applying very little compression, which results in huge files. Not only does this increase your storage needs, but it also does not make websites that allow uploading images happy, as you are potentially increasing their storage and bandwidth costs as well. While many websites have gotten smart about letting people upload huge images by applying compression on them, very few sites do it smartly. So why waste all that bandwidth and storage by exporting to 100% all the time?
My baseline recommendation is to use 77% in Lightroom, or value 10 for JPEG compression in Photoshop. It often results in roughly 200% or more in space savings and usually preserves enough detail in the scene without adding visible artifacts. There are rare situations where 77% can create banding in the sky, so if you see such problems, bumping up by one level to 85% will usually take care of that. I practically never use anything higher.
For a lot of photos though, even 77% can be overkill. If you look at the above table, going below 10 results in pretty significant space savings. If you want to reduce the image size even further, try pushing quality down to 62% or even 54% to see if the result is acceptable. Please note that the results will vary from image to image. Some photographs will do fine at low compression levels, while others won’t look their best.