Started 3 months ago | Discussions thread
Lan Senior Member • Posts: 2,465
Re: DNG vs ARW

henryk1 wrote:

Thanks to all. I think I'll stay with .ARW

Good choice

One of the big problems with DNG (from my perspective) is that whilst a DNG can contain raw image data, they don't have to. DNG is a container format, and in addition to raw data, it can just contain JPEG and/or TIFF images. Theoretically you could just store JPEG image data in there, and it would still be a valid DNG file.

If you edit an image on a pixel level, and then save as a DNG, the likelihood is that you're getting baked demosaiced data in your DNG, and not the raw data you might be expecting to find.

If you're lucky the DNG file may also contain the original raw file as well, as it does have an option to embed the original raw file, but then your file sizes will be somewhat bigger than they might be...

From an archival perspective, any format which is adequately documented now, (i.e. ARW) should be possible to open at any time in the future. If you're worried, save a copy of source code of something which can open and process the images now; i.e. the source for libraw; which is free, and takes up just 1.5MB, which is far less disk space than you need to store a single camera JPEG, and should allow you to read the format at any time in the future:


Libraw can currently read up to A7M3, A9M2, and A7R4 (and most older Sony/Minolta cameras that shot raw).

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