Opinion on Raw to DNG


Today’s Question: What do you think of converting raw to Adobe DNG?

Tim’s Quick Answer: There are certainly some benefits involved with converting proprietary raw capture files to the Adobe Digital Negative (DNG) format. However, my personal preference is to retain the original proprietary raw capture files, and not convert to DNG.

More Detail: The Adobe Digital Negative (DNG) file format was created in part to provide an openly-documented alternative file format to proprietary raw capture formats. The DNG format retains the key benefits of raw capture, without the proprietary nature of those raw capture formats.

Some cameras offer the option to capture photos directly into the Adobe DNG file format. In addition, Lightroom Classic provides an option to convert to DNG when importing proprietary raw captures, or to convert those raw captures to DNG later in your workflow.

One of the common reasons photographers might consider converting their raw captures to the Adobe DNG format is the proprietary nature of raw capture formats. The idea is that if at some point in the future all software capable of processing raw captures were to disappear, you could still access your Adobe DNG images. Even if Adobe were to stop providing software that could process Adobe DNG files, since the format is documented someone could create custom software to process those images.

This sort of issue is not something I am at all concerned about, since so many software applications (including Adobe’s applications) have been able to interpret the proprietary raw capture formats.

There are two other key potential advantages of converting to Adobe DNG. First, lossless compression applied to Adobe DNG files means the file will typically be around 20% smaller than the source proprietary raw capture, without losing any pixel data. This is obviously an advantage in terms of storage requirements. Note that you may get better or worse compression results depending on the specific file formats you are processing.

The other potential advantage of the Adobe DNG file format is that unlike proprietary raw captures, with DNG files you can save metadata updates directly in the DNG file. With proprietary raw captures metadata updates will be saved in XMP “sidecar” files rather than within the source raw capture.

Of course, I consider it a bit of an advantage for my workflow to have metadata updates stored separate from the original raw capture. For example, with a typical incremental backup solution if you update metadata in a DNG image the entire file would need to be backed up again. When only an XMP file gets updated with metadata changes, only the very small XMP file needs to be updated for an incremental backup, while he source raw image would not need to be backed up again, because the file will not have changed.

So, on balance I prefer to retain my original raw captures, rather than converting those captures to DNG. In addition, I simply feel better keeping my original raw captures, rather than converting them to DNG and potentially discarding the original raw files.