Does converting to DNG degrade images?

[snerkler]

I've just bought the Sony A7R IV and uncompressed raw files are huge (approx 120mb) and converting them to DNG using adobe's DNG converter decreases the file size to around 60mb, which is interestingly similar to Sony's compressed raw file size.

Now my brain tells me that if you convert a 120mb file to a 60mb file some data is lost somewhere, or does DNG act as some kind of lossless compression? 

So the question is, am I losing any image quality, colour or anything else by converting to DNG?

[Test Screen Name]

There are lots of ways to do lossless compression that might give that kind of saving. Run length, ZIP, and others. A lot of space is wasted by turning off compression, but nothing is gained...

[snerkler]

Thanks for the reply. I'm not exactly sure what you're saying here though, are you saying no data is lost by converting to DNG?

[JP Hess]

The DNG file container designed by Adobe is just a standardized container for the same raw data. I have compared DNG files against original raw files from my camera and have not ever been able to determine any deterioration in image quality. Difference in file size varies from one manufacturer to another. Some manufacturers are noted to be reduced by as much as 50% while others are reduced by much less. My Nikon NEF files only seem to be reduced by about 25% when converted to DNG. But as I have stated, I have never been able to determine any deterioration in image quality in the resulting DNG files. In my opinion, it isn't anything to be concerned about.

[snerkler]

Thanks for the reply. Since posting I found this article and it suggests the same as your findings. I'm going to use DNG from now on.

https://theblog.adobe.com/dng-pros-cons-and-myths/

[TheDigitalDog]

Depends on the kind of DNG you convert to but if lossless, no data loss to degrade image quality, smaller due to better compression usage.