JPEG size after BQM

[frederic chaume]

Hi

I created a workflow in BQM just to add a watermark (using a png 
filewith and opacity of 75%) .
Then I add a JPEG and I got the expected result but I realized that the 
size of the orginal JPEG was ~12Mb and the generated file is only ~4Mb . 
I checked that the resolution remains the same , so I'm wondering is 
there should be some comperssion during the BQM execution. Did I miss 
something?
For information, I did  the same in another software (DXO) and the 
generated file has the same size than the original one

thanks for your feedback

Frederic