Adobe are offering a free self-standing converter http://download.adobe.com/pub/adobe/dng/mac/DNGConverter_10_3.dmg
You can also save DNG from ACR or Lightroom, but using a converter over an original file is the cleaner way.
If you have some camera profile in ACR / Lr active other than Adobe Standard it may also boost lightness.
Adobe are offering a free self-standing converter http://download.adobe.com/pub/adobe/dng/mac/DNGConverter_10_3.dmg
You can also save DNG from ACR or Lightroom, but using a converter over an original file is the cleaner way.
If you have some camera profile in ACR / Lr active other than Adobe Standard it may also boost lightness.