DirtFarmer Loc: Escaped from the NYC area, back to MA

A recent post (https://www.uglyhedgehog.com/t-721844-1.html#12770262) on Topaz gigapixel forked into a dng discussion. Rather than hijack the original thread I thought it would be useful to continue the discussion in a separate thread.

Canisdirus posted a link to an Adobe article promoting dng. While Adobe is certainly interested in promoting their products, I don't think their arguments are all convincing to me.

"DNGs are easier to edit.
Editing a RAW file can be a challenge. You’ll need to use a sidecar or convert them to other formats first. A sidecar is a separate XMP file that contains all edits, changes, and settings. Essentially, this creates a separate file so the original RAW file remains completely untouched and unchanged. Sidecars are small, but they also mean that every RAW file is effectively stored as two files.

With DNGs, edits and changes are written directly into the file. This leads to fewer files for storage, but also strips out information that you can’t recover later."

Use of a sidecar file is not always necessary. Depends on your software (there IS good editing software outside of Adobe). The original raw file always remains untouched in a good editing program. If sidecars are used, they will most likely be in the same folder so there is no real problem dealing with them. Stripping out information to me does not seem like an advantage.

"Quality and file size.
DNG files are generally 15-20% smaller than RAW files, but the difference in quality is minimal. A DNG file can also save the original RAW file within itself. This doubles the size, but is also a nice safeguard.

DNG files also strip out select information to decrease the size and simplify storage and editing. This may include JPEG previews, GPS information, metadata, and certain camera models’ focal points, lighting, and picture controls."

The 15-20% size reduction has been challenged by many, who state that the size reduction may be as low as 1%. With dropping storage prices, is this really important?

"Memory and archives.
You can compress DNG files. This makes them much smaller than RAW files and ideal for storage and archives. Notably, the United States Library of Congress uses DNG files for this purpose. Another useful archival feature is that DNGs can self-check for corruption."

Again, storage. The inclusion of checks could be useful.

"Compatibility.
You can’t edit RAW files with third-party software. Further complicating matters, there are many types of RAW files. They differ by camera manufacturer, and in some cases, by sensor models. A RAW file from a Canon will not be the same as one from a Nikon. This can be even more problematic if you have a brand-new, high-end camera. It can take time for the software to catch up with your model.

DNG files course-correct for the wide variety of RAW file types available. As a single, open-source, highly compatible format, DNGs help to ensure that you’ll always be able to open your photo files — even if your camera brand stops supporting its native RAW file type. On the other hand, DNG files may not always work with the software that camera manufacturers produce for their own photographs."

Misleading. You can't edit raw data. I don't believe it is possible to edit the raw data from a dng either. The time delay between new camera introduction and updates to software is a valid reason to use dng, but it is not a long-term reason.

"Editing.
The simplest way to edit RAW files is by converting them to DNG. Depending on your computer, software, and how many photos you have, this could take hours and sometimes even days — but it’s worth knowing that you’ll always be able to open and edit your DNG file.

DNG files work well with Adobe programs like Photoshop and Lightroom. If you have many photos to edit, using DNGs can be a good idea thanks to built-in shortcuts and streamlined processes built into the files."

BULL. Yes, dng files work well with Adobe programs like PS and LR. But those same programs can handle the native raw files.

"Working with other photo editors
RAW sidecars may sound complicated, but they’re an excellent solution if you work with other photo editors. Provided you have the original RAW file, you can send the sidecar back and forth to work together on an image.

When using DNG files in collaborations, you’ll need to share the entire file and ensure it’s the latest version. This may present challenges over time, especially if you have a large number of files."

So you can do without using dng.

DirtFarmer Loc: Escaped from the NYC area, back to MA

I note that LR has features such as Pano and HDR that will generate a dng file. That's no real problem unless you want to edit the result outside of Adobe. (But of course you could send the result from LR to an external editor and edit that way). You still have the original file in the original format.

Rongnongno Loc: FL

One omission that is a dealbreaker.

DNG encapsulate almost anything, including JPG.

That makes it a dangerous hybrid folks confuse with true raw captures.

In my opinion, DNG is a junk format, if only for that.


 

JPG 10.4 MB

(Download)

DNG - 11.6 MB
Attached file:
(Download)

DirtFarmer Loc: Escaped from the NYC area, back to MA

I also note that LR will not convert a jpg to dng on import. (Just tried it and got an error message. It imported the original jpg).

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

I've never been a fan of dng. Native raw files are the way to go. Some advocate using dng as a solution when LR/PS do not support a recent iteration of a raw file, but I think it's a mistake. I would not recommend substituting a dng for raw, but rather as a temporary alternate, alongside the original raw file. This approach keeps all options on the table.

Some software like DXO and ON1 can be used as a "preprocessor" for a raw file. In DXO's case, you can open a raw file using plugin-extras in LR, edit the file in DXO Photolab and use its excellent Prime image enhancement, then send a dng back to LR, adding it to the catalog next to the original, and yes, LR can read it like a "native" dng. As such, I have no other use for dng.

Rongnongno Loc: FL

If you ACR in LR it will export to DNG and other formats.

lamiaceae Loc: San Luis Obispo County, CA

You make a convincing argument and points that I have read before. My main reason for using DNGs is it is A Native raw format for Pentax but I have also used the Pentax proprietary True Raw format too. What I really would like to know is what do the Side Car files do for ME. I work my images as PSD files with Ps CS6 and store them that way or as TIFFs. I tend to move image files from folder to folder, what happens when I don't move the side car files or I delete them? I don't really see a difference in any open images.

DirtFarmer Loc: Escaped from the NYC area, back to MA

The value of the sidecar files is in re-editing or moving from one editor to another. Since the sidecar files are text files you can look at them to see what's there. If you do that you will see that they have a list of edits, with an edit feature associated with a number. That defines the strength of that feature applied to the edit.

Obviously, if you're using editing programs from different software writers, trying to use the number from one program to another may present problems since the algorithms are not likely to be the same so the results of strength 37 in one program will not be the same as strength 37 in another. So I would say that the sidecar files will be useful in moving between Adobe programs, but not necessarily from Adobe to C1.

If you use LR, the edits are contained in the catalog, so the sidecar files are a duplicate. If you move from LR to PS you can select "Edit a copy with Lightroom adjustments" so the sidecar files are not necessary. If you send a raw file directly to photoshop outside of LR, the sidecar files will tell PS what edits you made in LR.

If you move (exported) image files from one folder to another, they are standalone files and the sidecar files will not have anything to do with them. The sidecar files will only be used in an editor.

If you're using dng as a native camera format, I don't see any problem. It's just that I don't see any advantage in converting from another raw format to dng.

CHG_CANON Loc: the Windy City

I like DNG for 'transfer' of data from LR catalog to LR catalog, so people can share their edit status and share the image work-in-progress LR settings back n forth. As a replacement / improvement for RAW, the DNG is only relevant for the short period of time between a new camera release and Adobe's release of support for that new camera. Beyond these two useful situations, there's no reason to always by default to convert your camera RAW to DNG.

selmslie Loc: Fernandina Beach, FL, USA

Yes and no. Clearly, encapsulating a JPEG or TIFF in a DNG does not make it raw. But there are other cases.

1. Encapsulating an actual raw file in a DNG can let you develop a raw image with software that may not support your particular camera.

2. It also allows me to skip the demosaicing process for a camera that has had its color filter array removed. While this is a special case, rarely needed, it's indispensable.

lamiaceae Loc: San Luis Obispo County, CA

Thank you, helps.

frankraney Loc: Clovis, Ca.

I think of jpegs as like a print. Dng is a negative. You can't go backwards. That's why I KEEP the original raw files.

Jmo

DirtFarmer Loc: Escaped from the NYC area, back to MA

A question for those who use dng and LR regularly:

LR allows you to produce virtual copies with different edits.
Since dng stores the edits in the file, do you then get two copies of the dng? Or does LR just select the non-virtual edit to store in the dng?

lreisner Loc: Union,NJ

One major benefit of XMP files is that they are a back up to your catalog. So if the catalog gets corrupted before being backed up, not all is lost. I use to convert my images to DNG, but I stopped.

DirtFarmer Loc: Escaped from the NYC area, back to MA

Since no one responded I tried it out. Generated a pano from a couple images, which produced a dng file. I then made a virtual copy and edited it so it would be recognizably different from the original pano dng. Looked in the folder where the original pano dng was located and there was no copy, so the virtual copy is truly virtual. And so although the dng file contains the current edits, virtual file edits are not stored in a separate file.

So the dng does not always store the current edits in the file.