content: Looks more like sensor noise to me than JPEG artifacts. I took this photo in 2014 so I can't say 100% but usually I just take the .DNG raw file into Photoshop and export a .PNG after tweaking the exposure and WB if necessary. I just looked and the original image is saved as a TIFF and there is the same kind of noise. I don't have the .DNG anymore but it would probably be present there as well.