– Both lack flat-field correction
– Both provide incomplete matrix-only color profiling: no DCP
– Neither use compression
– HTC One M9 DNG is 10 bit stored in 16bit uncompressed data: 39MB per 20 Mpixel image.
– LG G4 DNG is 10 bit stored uncompressed, 20MB per 16 Mpixel image
– Both have non-optimal noise profiling settings: HTC One M9 set noise reduction too high and LG G4 lacks noise profiling entierly.
Notes on flat-field correction:
Mobile camera modules require such correction to correct both vignetting and color cast (like pink spot / greenish or blueish corners).
HTC One M9 requires less correction than the LG G4.
It is only possible to compensate for light fall-off, in RAW image editors, not color cast.
As a result, the color cast in corners is essentially non-fixable.
Attached: the #LGG4 DNG sample provided by rendered in Lightroom with only modification an increased contrast and exposure slightly, to make both vignetting and color cast more obvious.
The least I can say is that there's room for improvement, both DNG implementation being non-optimized and incomplete.