Why does PSP Save As max quality enlarge a jpg file?

[SJS]

I don't know if this a good or bad, but I am surprised by the increase in file size using Save As jpg max quality. Files almost double in size even without any editing.

NOTE that I have the preference to Save Edit History in Metadata turn OFF.

I opened an unedited 4.5 meg jpg photo, and without any editing, PSP 2023 shows that Save As max quality will save it at 9.3.

My preferences will save the changed color space when I save a photo from my phone.

Is this just the right thing for my settings of no compression plus EXIF & ICC profile? Or something else?

[LeviFiction]

Max quality or losselss no compression should result in a larger file size, yes. Without getting into the nitty gritty, jpegs do a lot of creative work to toss out information and save as little info as is necessary to recreate the image. This can be as simple as taking a giant blue sky and reducing it down to just a few squares that get repeated a large number of times, to getting rid of color variations, and getting rid of colors altogether that we usually don't see very well. So when you decrease the compression and increase the quality, it does less of that. Keeping more colors, and more pixels, so you end up with more information inside the file making it bigger.