What is the best way to process a jpg

Will LR Mobile treat a jpg the same way as LR CC? What I mean is that the original will not be modified?

Lightroom does not modify your original photos. It doesn't matter if they are JPG or RAW, and it doesn't matter if you are using LR CC or LR Mobile.

A RAW file as captured by the camera's sensor (because that's what a raw file is: minimally modified data from the sensor) cannot be reconstructed. The in-camera treatment tries to output a finished file to be used as this. The decisions by the algorithm are destructive. And then you have the JPEG compression which reduces the data literally to the absolute minimum. This treatment is again irreversible.

All this is OK for a final image, but not optimal for images that still need to be modified. You have to live with those restrictions as long as you do not get access to the raw data file.

Now the best method to work JPEG images in LR is to keep them JPEG and to work whatever you want to do and live with the JPEG restrictions (especially compression artefacts). As LR is nondestructive, you can adopt this workflow without regrets. As soon as you need to transfer your file to Photoshop, continue working with a TIFF file. Just avoid JPEG iterations as the JPEG induced error accumulates with each iteration.

Yes: an imported JPG file is worked FROM, rather than worked ON - in Mobile the same, as on the desktop.

Approximating a Raw file: that depends on how you have taken the picture. You may want to set the JPG settings for reduced contrastiness and avoid using any special effects or filters.. To get the highlights etc which are most conducive to being adjusted.

And in low light, with JPG you pretty much have to make the shot either "about" the highlights, or the shadows, each at the expense of the other. For stationary scenes consider exposure bracketing and also try out the HDR options supplied - some phones' HDR feature allow you to keep the component shots as well as a combined image that the phone itself has processed. Remarkably good results can sometimes be got from exposure-fusing or blending multiple original JPGs - that will need to be done on the desktop, in due course. But if an in-phone HDR gives a better immediate basis for further work, so much the more convenient.

daisyg30458525  schrieb Is there some way to extract the data in the jpg so that we can approximate a raw file? What would converting a jpg to dng do?

There's no way, because jpeg is a compressed format and there a lot of picture informations are lost. This can't be restored.

The converting form jpg to dng makes no sense. The picture informations that are lost in jpgs and will be lost.

Axel