# JPEG: Copy to DNG?



## Martin van Gog (Dec 27, 2016)

Hi,
I am considering to buy a new camera for nature photography. From macro to telephoto. My dealer advises me a Nikon Coolpix P900, so for around 600 euros.

This device has the drawback, it shoots only JPEG. That means I can not change anything in LR concerning the white-balance as shot, schadow / high-lights recovery.

If I make use of the option: Copy as DNG, can I adjust the white balance or/and similar?

As solid thanks for replying to this post. Martin

Almere, the Netherlands


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## clee01l (Dec 27, 2016)

No.   DNG is an all embracing format.  It includes RAW data which has not been converted to RGB as well as RGB data (like JPEGs).  The data can be compressed or uncompressed, lossy or lossless.  Smart Previews are lossy DNGs.
When an app like LR opens a DNG file it first inspects metadata in the file header to determine the type of data stored in the data block.  If that data is linear mosaic'd data, LR uses ACR to demosaic the data and convert the values in the Photosites to RGB Pixels.  If the data is already RGB pixel data, then LR simply uncompresses it if necessary and displays the pixel data.


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## Johan Elzenga (Dec 27, 2016)

As Cletus explained, DNG can contain different kind of image data. It can contain raw data, but it also can contain RGB data. If you convert an image to DNG, the original image determines what the DNG will be. So if the original was JPEG (which is RGB) then the DNG will be RGB, not raw. The image quality will also not improve, because the lossy compression of the JPEG was already done when the JPEG was created in the camera. In other words, converting JPEG to DNG is pretty useless.


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## johnbeardy (Dec 27, 2016)

The value of converting the JPEG to DNG is:

- safeguard against the risk of destructive editing (eg editing the JPEG in Photoshop and saving edits back to the original)
- checksums for long term data-integrity checks
- Lightroom edits visible in other apps by updating the DNG's embedded preview
- minor ones include the DNG file extension signifying that the file is an original


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## Martin van Gog (Dec 27, 2016)

I'm aware of the DNG characteristics. What I meant was,  I have more post-processing opportunities after conversion from JPEG to DNG? Adjusting white-balans, recovery shadows and highlights e.d.

Or do I seek refuge in PhotoShop?

With Regards, Martin


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## Hal P Anderson (Dec 27, 2016)

As Johan pointed out, you don't gain any new processing opportunities by converting to DNG. Lightroom _will_ allow you to modify the white balance on a JPG file. However, if the JPEG has blocked highlights or shadows, you can't recover them using _any_ post-processing app. Personally, I'd buy a camera that shoots raw.


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## clee01l (Dec 27, 2016)

Neither Lightroom or Photoshop is going to help you.  If you convert to DNG, all you have is a lossy JPEG file in a DNG wrapper.   Once an image is converted to RGB, things like White Balance, tone adjustments get "baked in".   You can nudge the values a little bit in either direction but nothing like the dynamic adjustments that you get when converting the RAW to RGB the first time.


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## Johan Elzenga (Dec 27, 2016)

Martin van Gog said:


> I'm aware of the DNG characteristics. What I meant was,  I have more post-processing opportunities after conversion from JPEG to DNG? Adjusting white-balans, recovery shadows and highlights e.d.



You have the same post-processing opportunities as with JPEG. Adjusting white balans: you can adjust the color balance, which is more or less the same. Adjusting shadows: yes, but that will quicky introduce noise (more than a 14 bits raw file would). Recovery of highlights: no, what is clipped, is lost forever.


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## johnbeardy (Dec 27, 2016)

The benefits are archival or DAM-related, not image quality.


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## Tony Jay (Dec 28, 2016)

To me the question is much more related to camera choice rather than merits of converting JPEG's to DNG.
I simply feel that the camera model mentioned is hopelessly inappropriate for the purpose and the drawback that it only shoots JPEG's is merely the most obvious problem that the OP has discovered.

I would not want to make specific recommendations but there are any number of better alternatives even taking into consideration the budgetary constraints.

Tony Jay


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## Fraunt Hall (Dec 28, 2016)

Please, lets clarify:

1.  It is my understanding that editing DNG conversions from native camera RAW files using Lightroom or Adobe Camera RAW does NOT act destructively on the pixels of the DNG file, but can either, depending on the user's choice, embed the edits inside the DNG file or create a sidecar file to that DNG file with the edits, without changing or damaging the pixels in the DNG file.  This then permits the user to re-edit the DNG file or even reset the edits to a nominal "zero edit" state. pr add new edits.  If this is wrong, it needs to be clarified.

2. I would like to know whether or not using LR or ACR to edit a jpg file is a non-destructive process demonstrated by creating an XMP sidecar file with any edits done to the jpg.  If this is correct, then LR or ACR edits essentially circumvents the lossy nature of jpg images.  Perhaps this is also wrong.


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## Johan Elzenga (Dec 28, 2016)

Fraunt Hall said:


> Please, lets clarify:
> 
> 1.  It is my understanding that editing DNG conversions from native camera RAW files using Lightroom or Adobe Camera RAW does NOT act destructively on the pixels of the DNG file, but can either, depending on the user's choice, embed the edits inside the DNG file or create a sidecar file to that DNG file with the edits, without changing or damaging the pixels in the DNG file.  This then permits the user to re-edit the DNG file or even reset the edits to a nominal "zero edit" state. pr add new edits.  If this is wrong, it needs to be clarified.



Lightroom *never* damages pixels, regardless of what file type the image is. The edits are stored in the Lightroom catalog only, unless you check the preference setting to write changes to XMP as well. If you use ACR, the edits are either stored in XMP or in the central ACR database (that is a preference setting in ACR).



Fraunt Hall said:


> 2. I would like to know whether or not using LR or ACR to edit a jpg file is a non-destructive process demonstrated by creating an XMP sidecar file with any edits done to the jpg.  If this is correct, then LR or ACR edits essentially circumvents the lossy nature of jpg images.  Perhaps this is also wrong.



See above. However, LR or ACR edits do not essentially circumvent the lossy nature of jpg images, because that damage was already done when the jpeg was created. What you can say is that LR and ACR do not *further* damage the jpeg because they use non-destuctive parametric edits.


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## Tony Jay (Dec 28, 2016)

Fraunt Hall said:


> Please, lets clarify:
> 
> 1.  It is my understanding that editing DNG conversions from native camera RAW files using Lightroom or Adobe Camera RAW does NOT act destructively on the pixels of the DNG file, but can either, depending on the user's choice, embed the edits inside the DNG file or create a sidecar file to that DNG file with the edits, without changing or damaging the pixels in the DNG file.  This then permits the user to re-edit the DNG file or even reset the edits to a nominal "zero edit" state. pr add new edits.  If this is wrong, it needs to be clarified.
> 
> 2. I would like to know whether or not using LR or ACR to edit a jpg file is a non-destructive process demonstrated by creating an XMP sidecar file with any edits done to the jpg.  If this is correct, then LR or ACR edits essentially circumvents the lossy nature of jpg images.  Perhaps this is also wrong.


Welcome to Lightroom Forums!

With respect to the questions asked:
1. The same editing process is used by Lightroom irrespective of the file type. So a parametric editing process is always used. XMP sidecar files can only be generated if proprietary raw files are being edited AND edits are saved to file. No XMP sidecar file is ever generated if a DNG file is being edited.

2. As per (1.) editing a JPEG will not generate an XMP sidecar file. All file types apart from the proprietary raw files can potentially have the edits stored in metadata fields found within the file structure itself. Pixel data is never manipulated. However, in Lightroom, all the edits are stored within the catalog. One, specifically has to do a Ctrl-S or Cmd-S to save the edits to file otherwise the only place those edits are stored is in the catalog.

With respect to JPEG files and editing in Lightroom: There are no limits as far as slider manipulation goes when compared to other file formats.
However, JPEG files only contain 8-bits of tonal data and the white balance is essentially baked in. As a consequence these files will tend to fall apart if vigorously edited. The usual consequence is banding where there are visible steps in colour or tone across an image instead of an imperceptible gradient. Altering white balance will often result in a hideous image with some very strange colours. This is because, unlike a raw image where the white balance is not applied to pixel data but rather stored as a metadata item, in a JPEG the white balance is applied at a pixel level and actual colour data is altered at a pixel level.

With respect to the lossy compression applied to JPEG's: Since Lightroom never alters the master file because it uses a parametric editing process then yes, the file is not degraded. However creating a derivative JPEG from another JPEG will result in some degradation in quality.

Tony Jay


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## Fraunt Hall (Dec 29, 2016)

Very informative and my understanding has been broadened.  A valuable forum. Thanks for your welcome and information.

Fraunt Hall


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