Advantages/ disadvantages of DNG vs RAW or JPG

What are the advantages/ disadvantages of converting my files to DNG from RAW or JPG (if possible) formats

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Photography, It ain't the same old Art form it used to be....

Canon 30D
Battery Grip BG-E2
Canon 18-55
Tamron 28-75 2.8
iMac 24ich 3.06GHz NViidia 130GT 1T HD

That's a big question, and one that is difficult to answer on a forum. I don't know what software you are using or plan to use, so the answer will be very general. A raw file from a camera has anywhere from 10 to 14 bits of information, so there is a lot more image data. The raw conversion software that you use has the capability to recover more detail in the shadows and highlights, and it is much easier to control White balance in a raw image. Every camera model creates its own special version of a raw file. Consequently, raw conversion software must be able to identify what model took the picture. Because of that issue, sometimes it is necessary to wait for a new version of the raw converter in order to be able to develop those raw images. I say "develop" because a raw image is more like a negative.

The DNG file format has been developed by Adobe. They have provided a free converter that will take the raw image data and put it in a standardized container so that the file no longer has to depend on specific versions of software. This sounds like a great idea, but some manufacturers are not buying into the idea. A lot of people like to convert to DNG because they feel that since it is an open format that is well documented it will be around for quite a while. I'm still undecided on that argument.

A JPEG image is what I consider a final image. All of the settings have been "embedded" into that image making it more difficult to do some types of adjustments. You should do all of your editing on a raw image, regardless of whether it is the original raw file from the camera or a converted DNG file. The image data is the same in either file type. Then you can create JPEG images for sending to a lab, or for e-mail, or for posting on the Web, or what ever. My personal preference is to do as little editing on JPEG images as possible. That's why, in most cases, I shoot raw images and then create JPEG images for specific purposes. Generally speaking I consider JPEG images disposable; I get rid of them after they have been used for whatever purpose they were created.

Sorry, that is a very general answer.

Pretty sure you can't go from JPEG to RAW or DNG. As mentioned, RAW and DNG will have more bit depth, which is good if you are doing any type of "involved" processing. For snapshots, JPEGs are fine.

I'm fortunate in that my camera will create both JPEG and RAW or DNG files at the same time. I use the JPEG as browse images and process the RAW/DNG to my liking. Instead of the propriety RAW format my camera produces, I opt for DNG output because a lot more software programs accept DNG than my camera's RAW format.

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Steven
GMT -8

I appreciate what Adobe tried to do with DNG however, Adobe dropped the ball. In my view it is no more of a long term guaranteed access format for your images than the format used by your camera. In other words I see no point in converting to DNG.

As for converting JPG to DNG, it can be done. However, IT DOES NOT make that JPG a raw file. It is simply a bitmap (jpeg) in a DNG wrapper. Myself I do not recommend converting bitmap images to DNG because in the future you are going to have a hard time remembering which are real raw and which a JPG in raw clothing. I would save JPGs as TIFF images. I don't save anything in JPG unless it is going on or over the net.

Robert

--

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Thanks for your answer was good info,
Currently using LR3 with a canon 30D

I see I can convert my RAW files to a DNG but would still want to hold onto the RAW files

Canon 30D
Battery Grip BG-E2
Canon 18-55
Tamron 28-75 2.8
iMac 24ich 3.06GHz NViidia 130GT 1T HD

--
Photography, It ain't the same old Art form it used to be....

Canon 30D
Battery Grip BG-E2
Canon 18-55
Tamron 28-75 2.8
iMac 24ich 3.06GHz NViidia 130GT 1T HD

YOu can do both

My workflow is as follows

USE RAW only in camera

On Import convert to dng

but at the same time get LR to send second copy (archive) to external drive as CR2.

DNG files are able to store PP info in the file instead of using Sidecar File.

I still have the original CR2 archived.

Converting JPG to DNG to me is pointless.

DNG = digital negative. JPG as previousl poster says is final, so why convert JPG final back to a negative. If you want to edit and save JPG then convert them to tiffs, then edit and when edits are complete same back as JPG.

If you only edit in LR then it is non destuctive anyway so justleave the JPG's as JPG.

Hope that helps in your decision. There is quite a lot of differing views on the use of DNG but I am an avid supporter but many are not.

Just for the sake of discussion. And, depending on your workflow, I understand that some of you will disagree with me. However, in the standard default mode, Lightroom does not create an XMP sidecar file for proprietary raw images. The changes are stored in the catalog. The argument for converting to DNG so that there isn't a sidecar file is a weak argument. In Lightroom, the only time you have a sidecar file is if you choose to create one. If I'm going to transfer some raw images to another computer then I will sometimes export DNG copies so that the settings are embedded in the image file, but to routinely convert all raw files to DNG seems rather pointless to me. I realize that those who present on Adobe.TV are all excited about the DNG format. But I don't use it most of the time. It doesn't say enough space to really matter. And I don't believe that the DNG format is any more future-safe than are original raw files.

Yeah your correct on all counts.

But after a long investigation into the pro and cons of dng i decided to go down that path.

After all I am still archiving my original CR2 files so to some extent I have the best of both worlds.
SO I have 2 backups of my DNG Files and 1 Archive of the original CR2 file.

The fact that a number of manufacturers (Including Leica) use DNG as theire raw format was one of the tipping points for me and hopefully the fact that the processed data is stored in the file may just mean that some future software purchase may also be able to read that info negating.

As it stands with CR2 (or NEF for that matter) the software would have to be able to read the sidecar file becasue it certainly wouldn't be able to access LR catalogue and find the associated info for the file.

Maybe I am dreaming but it seems to me if DNG did become more popular and sofware packages accessed the saved info, it would mean that processing info would be available across software progs and platforms. I can only live in hope. I haven't checked but some software may already do this.

I did not take the decsion lightly and have no issue whatsoever with those who choose to continue to use their native RAW format.

And, Adobe, Canon and Nikon certainly are not going to stop supporting CR2 and NEF any time soon.

One other reason that I went down the path is that I use CS3 with ACR 4.7 and so my 7D CR2 files are not supported. So converting to DNG with LR3 also solves this issue for me. LOL - not that I ever use CS3(ACR) direct with DNG anyway as I always "Edit In PS" from LR3 but I can if I ever want to. I do not use PS enough to bother upgrading.

Cheers
and thanks for the comments - a very interesting discussion point.

Questions on how future-proof are DNGs are valid but I suspect that Adobe will look after DNG users better than most general RAW converters who may well not bother to support old RAW formats in the future.
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Keith-C

Having the sidecar files stuck inside the LR catalog is only good if you stick with LR only... having the info embedded into the actual files is a much better solution if you use other software packages.

Another example.... I recently built a new computer and decided to rebuild my Idimager database rather than use the existing one (speed issues). So, I was able to easily read the sidecar file info that was embedded in all JPG and DNG files on my system and after 10 hours or so... had a new instant catalog. I would not have been able to do that had the data been trapped inside LR without building new files with that data... something I don't think is a good idea.

Who knows what software will come out soon... having all data embedded within the image is always a preferred choice to allow you to use that software instead of being tied into LR..

Jim Hess said:

The argument for converting to DNG so that there isn't a sidecar file is a weak argument.

Click to expand...

I beg to differ. I'm a Lightroom user, and recently had a hard drive crash. With the help of "Data Rescue" I could recover most files. Raw, tif, jpg, dng, psd... no problem. But none of the recovery softwares I used was able to recover any of the actual Lightroom catalogue files on the broken hard drive. (there were about 10 LR catalogues on there).

So in that sense, I was lucky that ALL my info was embedded in the DNG files. And as I mainly work with smart collections in Lightroom (based on star ratings/label colours/embedded keywords/...), it was easy to reconstruct the LR catalogue file from scratch.

BSHolland said:

So in that sense, I was lucky that ALL my info was embedded in the DNG files. And as I mainly work with smart collections in Lightroom (based on star ratings/label colours/embedded keywords/...), it was easy to reconstruct the LR catalogue file from scratch.

Click to expand...

In what way would you not have been OK if the sidecar file had been saved in XMP sidecar files, instead of into DNG files directly?

There are two questions here:

• should metadata be copied to the file system as well as being stored in the LR Catalog; and if so:
• is it inherently better to save metadata into an updated DNG file, rather than into an external XMP file alongside a completely untouched Raw file?

The fact that a Catalog file can be lost or corrupted is relevant only to the first question, and is easily answered: a redundant up-to-date copy of the metadata cannot do any harm except (slightly) to LR performance. Also doing this may allow other programs (such as Photoshop) which understand the Adobe proprietary metadata, to "see" your adjustments made in LR. This is all regardless of whether the metadata is saved inside a DNG, or in an accompanying XMP sidecar.

Personally, I have LR write out its metadata automatically. I generally opt for proprietary Raw, not DNG. This means that whenever I backup my LR data folders, by Syncing them to an external disk, all the updated images involve just a few Kb each that need to be copied across - overwriting the previous version of the XMP for that image. I don't need to backup an entire DNG file including all the sensor data for each changed image, merely because some metadata has changed.

If DNG becomes an overwhelmingly good idea in the future, I can easily get LR to put the images into DNG (including the adjustments) then.

However if I had already converted to DNG and then regretted that, and wished that I had the proprietary format instead (say, if I wanted to use Bibble which AFAIK does not support Adobe-converted DNG) - then I would be worse off because of having made the conversion. ATM there is no route AFAIK by which I would be able to re-convert DNG back to the starting format. I don't like to paint myself into a corner like that needlessly.

RP

Some recovery software will not keep filenames intact, hence sidecar file names will differ from the respective raw file name.

You should save the original untouched RAW file, convert to tif and process that, then produce whatever jpgs you need from the final tif image. Don't waste time with other types of files.

sidecar files = one more thing that can get misplaced, corrupted and unlinked from the original. What if you want to rename our files.. you better ensure you rename the sidecar too... extra unnecessary risk.

insightful? why are DNG files a "waste"?

Skipper494 said:

You should save the original untouched RAW file, convert to tif and process that, then produce whatever jpgs you need from the final tif image. Don't waste time with other types of files.

Click to expand...

Yes, and I also think that MY workflow is the ONLY one that's right. There are NO other workflows worth considering besides MINE, because I was spoon-fed EVERYTHING there is to know about file types.

This is an interesting question to me as I dont yet have a substantial catalogue of images so I would like to get off on the right foot, I use Lightroom and thought I might approach it this way...

Import the RAW image and make whatever adjustments are necessary
Export JPEG for printing
Export final version to DNG for archiving

Have I missed a step or overlooked anything with that thinking?

fuego6 said:

sidecar files = one more thing that can get misplaced, corrupted and unlinked from the original. What if you want to rename our files.. you better ensure you rename the sidecar too... extra unnecessary risk.

Click to expand...

A Lightroom user will usually move images around and rename them inside LR, because to do so externally would invalidate the file links in LR's Catalog. However I can't think when I have last done any of that. It just doesn't arise.

When LR manages image source files in some way, any XMPs follow along automatically - Raw+JPG pairs too. I believe Bridge does the same - it's some time since I have used Bridge, though, so I may be mistaken.

Compared with an ACR user, a LR user would be less at risk of, and also more relaxed about, losing external XMP data somehow. This is all an optional redundant copy of a subset of the data in the LR Catalog anyway (there may be other Virtual Copy metadata sets, for example, not written to file - and perhaps the preferred version of the image is one of these anyway).

I can quite see that this issue may be more crucial for an ACR user, for whom this may be the only metadata copy in existence - and who is typically more likely to manually move items around in a file browser, because more reliant on file location and naming in order to keep track of images and image versions.

There is some practical logic to a functional separation of metadata and image data; the "changing", and the "unchanging". At the same time, I can appreciate the competing attractions of having a self-contained file.

In LR the filename and the folder location are often of little interest really, and can be set up to get created hands-free, and there is little reason for the user to fiddle about with them, or even visit them using the OS directly. Image organisation can happen largely within the system, not externally at the file system level. And the image is what you see inside the program, not what you see outside the program. That's a second safety disconnect: between "virtual" and "physical" working.

RP