save pictures lossless into a BLOB

My report runs on macOs and Windows 10. The report stores incoming pictures (currently per Drag&Drop, later per TCP/IP) into a BLOB field of my database.
These pictures have usually the JPEG format.
Now I want to store the pictures with the same quality as the incoming pictures do have.
If I save the pictures with PNG format small pictures (round about 500 kB) becomes fourfold bigger.
If I save the pictures with JPEG format at highest quality level the pictures becomes twice bigger.

Is there a way to determine the quality of the incoming JPEG picture for avoiding the growth of the pictures?

If you open the JPEG into a Xojo picture object, then what you put into the database has little to do with the original image.

If you are getting a folderitem and want to preserve it intact ‘as-is’, you could read it into a memoryblock and push that as a string into the blob.