Exporting doubles size of jpg file, but I did no correction and a basic export

I exported a jpg file of 102 MB which had the properties shown below this message
I did no corrections at all.
I exported with the same resolution without resizing and with 100% quality.
The exported file had exactly all the same properties.
To my big surprise, the size of the exported file was 202 MB.
It had nearly doubled.

Of course, basically the same happens if I do some “small” corrections to the image.

Fortunately, when exporting the exported file again, there was not increase in size anymore.
The size remained exactly the same.

The original file is the output of a VIISAN A3 scanner.

How can I understand this?
How can I avoid this?
How can I reasonnably avoid this?



My first guess is a “mismatch” of the jpeg compression between viisan and dxo.

File properties

Colour Model: RGB
Depth: 8
DPI Height: 1.200
DPI Width: 1.200
Pixel Height: 19.842
Pixel Width: 14.031
Profile Name: sRGB IEC61966-2.1

Exporting a JPG at 100% always practically doubles the filesize. However, this is not simply a DxO issue, just about all image editors do this, also Adobe and Affinity. This is more a JPG issue. Google it, you will find more similar experiences in various editors.

You will not loose any quality whatsoever if you export at 90 or 80% and it will result in much smaller filesizes.

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It’s normal. Photolab at 100% uses absolutely no compression at all, which definitely is overkill: but I am glad that they implemented it correctly (which isn’t always true in other software). For me, 92-95% hits the spot for absolute quality while guaranteeing a huge file size saving.


This. Yes.

Thanks for the answers!
It just came to my mind that if the VIISCAN scanner had used DXO for the jpeg compression, then this strange issue would not exists.
It is interresting!
Maybe the jpeg standards are not perfect from this point of vue?