Ad
Ad
Ad
Pages: [1]   Bottom of Page
Print
Author Topic: Adobe DNG Converter and ACR  (Read 6943 times)
petercook80
Jr. Member
**
Offline Offline

Posts: 60


« on: September 24, 2010, 04:56:57 AM »
ReplyReply

Hi, I have just got a new canon camera and because I am running PS CS I am using the DNG converter to convert the camera's RAW files to DNG.
It all works well but I am wondering why the DNG converter has a setting to match the version of ACR that you use (2.4 in my case) , I thought the point of DNG was that its a universal format. It makes me wonder whats happening in the conversion and am I 'looseing' any fuctionality by converting with the ACR 2.4 option if in the future I upgrade my version of PS? (hope you can see what I am getting at)
« Last Edit: September 24, 2010, 08:16:03 AM by petercook80 » Logged
deejjjaaaa
Sr. Member
****
Offline Offline

Posts: 743


« Reply #1 on: September 24, 2010, 01:00:18 PM »
ReplyReply

It all works well but I am wondering why the DNG converter has a setting to match the version of ACR that you use (2.4 in my case)

because there were some additions to DNG specifications and older raw converters might not be able to use some new features.

and am I 'looseing' any fuctionality by converting with the ACR 2.4 option if in the future I upgrade my version of PS? (hope you can see what I am getting at)

you might be loosing a lot of quality (demosaicing/noise reduction/etc) by using a very-very old version of ACR (2.4)... and to be on the safe side you should always keep the original raw files as they were generated by your camera's firmware - in your case DNG might be OK as a part of your workflow (but you are locking yourself into an obsolete raw converter) - but if you value your raw files - keep the originals, not DNG files ... even Eric Chan from Adobe Labs says so :

http://forums.adobe.com/message/1210133#1210133

"...for archival purposes I recommend (and practice) safely storing the original raw files in the form that they came off the camera, whether they be DNG or non-DNG..."


Logged
01af
Sr. Member
****
Offline Offline

Posts: 294


« Reply #2 on: September 26, 2010, 06:09:37 AM »
ReplyReply

... I am wondering why the DNG Converter has a setting to match the version of ACR that you use (2.4 in my case). I thought the point of DNG was that it's a universal format. It makes me wonder what's happening in the conversion and am I 'losing' any fuctionality by converting with the ACR 2.4 option if in the future I upgrade my version of Photoshop?

You might be losing a lot of quality (demosaicing/noise reduction/etc) by using a very-very old version of ACR (2.4) ...

Using ACR 2.4 is not the same as converting raw files to DNG with ACR 2.4 compatibility.

When using the current DNG Converter with the backward compatibiliy option set to "Camera Raw 2.4 or later" then you're losing nothing. Instead, you're gaining something: maximum backward compatibility. When setting the compatibility option to "Camera Raw 5.4 or later" then you may lose something (actually, even then you're losing nothing with most cameras).

The actual quality loss occurs in the moment you're using old Camera Raw 2.4 to convert your DNG file to TIFF or JEPG. Camera Raw 2.4 uses an outdated interpolation algorithm and has limited controls and poor sharpening. With the current Camera Raw (or Lightroom) version you'd get better results. Anyway ... when switching to the current Camera Raw version then it doesn't matter which backward compatibility option your DNG files were created with. So when you use DNG Converter's "Camera Raw 2.4 or later" compatibiliy option today and switch to CS5 with Camera Raw 6 tomorrow then you are not going to lose anything. Remember---DNG Converter just converts from one raw format to another but doesn't do any demosaicing, so no losses here. It's Camera Raw which actually interprets the raw data and turns them into RGB data.

So---do not confuse the backward compatibility options in DNG Converter with actually using older Camera Raw versions.

Furthermore, you can always use the current DNG Converter to convert DNG files created with an old version of DNG Converter to the current DNG version. No need to keep the original raw files around. But that wouldn't make any difference in image quality because the actual raw data will be just the same. So just go ahead and use the "Camera Raw 2.4 or later" compatibility setting with confidence. That's what it's for.
« Last Edit: September 26, 2010, 06:14:59 AM by 01af » Logged
deejjjaaaa
Sr. Member
****
Offline Offline

Posts: 743


« Reply #3 on: September 26, 2010, 09:01:12 PM »
ReplyReply

You might be losing a lot of quality (demosaicing/noise reduction/etc) by using a very-very old version of ACR (2.4) ...

Using ACR 2.4 is not the same as converting raw files to DNG with ACR 2.4 compatibility.

When using the current DNG Converter with the backward compatibiliy option set to "Camera Raw 2.4 or later" then you're losing nothing.

You are wrong... for example take a raw file from Panasonic LX3 (as you know Panasonic wants raw converters to have optics correction enforced) and convert it to DNG w/ option set to ""Camera Raw 2.4 or later"... you will receive a linear DNG... linear DNG is demosaiced using a "simple bilinear interpolation" according to Eric Chan of Adobe Labs... so here we go  Grin... quality is lost (forever, if you did not save the original raw somewhere).

Logged
deejjjaaaa
Sr. Member
****
Offline Offline

Posts: 743


« Reply #4 on: September 26, 2010, 09:05:51 PM »
ReplyReply

Furthermore, you can always use the current DNG Converter to convert DNG files created with an old version of DNG Converter to the current DNG version. No need to keep the original raw files around. But that wouldn't make any difference in image quality because the actual raw data will be just the same. So just go ahead and use the "Camera Raw 2.4 or later" compatibility setting with confidence. That's what it's for.

see my posting above and do not make such recommendations anymore.
Logged
01af
Sr. Member
****
Offline Offline

Posts: 294


« Reply #5 on: September 26, 2010, 09:32:37 PM »
ReplyReply

You are wrong ... for example take a raw file from Panasonic LX3 (as you know Panasonic wants raw converters to have optics correction enforced) and convert it to DNG w/ option set to "Camera Raw 2.4 or later" ... you will receive a linear DNG ...

Indeed? Oh ... so I stand corrected.

Still, for most cameras the compatibility options don't make any difference. For some they obviously do---now I am wondering for which. Okay, Panasonic LX3 ... any others? I'd guess a few more Panasonics ... yet others?
Logged
sniper
Sr. Member
****
Offline Offline

Posts: 580


« Reply #6 on: September 27, 2010, 01:35:41 AM »
ReplyReply

Personally I'd always keep my original RAW, storage space is cheaper than ever these days, and why throw away something I may need one day.
« Last Edit: September 27, 2010, 03:35:23 AM by sniper » Logged
zhgtkwyy
Newbie
*
Offline Offline

Posts: 1


« Reply #7 on: September 27, 2010, 03:11:53 AM »
ReplyReply

thank you very much! It is useful for me!
Logged

petercook80
Jr. Member
**
Offline Offline

Posts: 60


« Reply #8 on: September 28, 2010, 08:24:56 AM »
ReplyReply

Thanks all for the responses, having read through and tried to digest the answers I am still not sure what to make of it all.
On one hand there is the suggestion that as each version of the ACR is better than the last that using the DNG converter with ACR 2.4 or later on will cause a loss of quality....
(quote from DEJA "for example take a raw file from Panasonic LX3 (as you know Panasonic wants raw converters to have optics correction enforced) and convert it to DNG w/ option set to ""Camera Raw 2.4 or later"... you will receive a linear DNG... linear DNG is demosaiced using a "simple bilinear interpolation" according to Eric Chan of Adobe Labs... so here we go  ... quality is lost") – I thought the ‘demosaiced’ stage was not done until you got to ACR !

On the other hand its suggested that nothing is lost in the actual conversion to DNG.

My personal thoughts are that I fully expected that later versions of ACR would perform better and give better results at converting a RAW (or DNG) file, but I was surprised that there might be quality issues with the actual conversion to DNG.  I thought DNG was a 'Standard' and that was the whole point of it, but the fact that you can convert into different flavours for versions of ACR would seem to indicate that there are different flavours of DNG, though whether this is to accommodate new tools and features of ACR  I am not sure.
  
Interestingly if I convert to DNG with compatibility to the latest ACR, ACR 2.4 still opens the DNG file (a note in the converter says older versions might open the DNG but it depends on the camera) so I am not sure if I should just stick with converting with compatibility set to the latest version of ACR.

At the end of the day I have ACR2.4 for now (I can’t afford to upgrade yet) but I am taking the option of embedding the original RAW file when I convert so I can always have access to it later if needed.
Logged
AFairley
Sr. Member
****
Offline Offline

Posts: 1129



« Reply #9 on: September 28, 2010, 10:51:38 AM »
ReplyReply

Personally, I would wait for Eric Chan (who actually works for Adobe in the ACR/DNG area as I understand) to weigh in on this issue.
Logged

01af
Sr. Member
****
Offline Offline

Posts: 294


« Reply #10 on: September 28, 2010, 01:16:14 PM »
ReplyReply

... I thought the 'demosaiced' stage was not done until you got to ACR!

It isn't indeed—unless you convert to Linear DNG which is a demosaiced format. That's why you normally avoid Linear DNG whenever possible. It's used as a last resort in those cases where the raw data for some reason cannot be represented in the regular DNG format.

While Linear DNG in principle does lead to data loss, for practical intents and purposes the losses usually are imperceptible.


Interestingly if I convert to DNG with compatibility to the latest ACR, ACR 2.4 still opens the DNG file ...

For the vast majority of digital cameras, DNG Converter's compatibility setting doesn't matter ... obviously, yours belongs to those (and the Panasonic LX3 doesn't). So for you, the compatibility setting is entirely irrelevant. Leave it at "Camera Raw 5.4 or later" (which is the default) and go ahead. Or set it to "Camera Raw 2.4 or later" (which formally is the proper option to choose in your case)—but it won't make any actual difference to your DNG files.

It DOES make a difference for some cameras. But not for yours.
« Last Edit: September 28, 2010, 01:18:36 PM by 01af » Logged
deejjjaaaa
Sr. Member
****
Offline Offline

Posts: 743


« Reply #11 on: November 24, 2010, 10:57:11 PM »
ReplyReply

While Linear DNG in principle does lead to data loss, for practical intents and purposes the losses usually are imperceptible.
then why bother with ever complex demosaic methods when we can just use "simple bilinear interpolation demosaic" (that is unless Eric Chan will update us that they changed the way DNG converter is working)... but I guess you will not agree yourself to use that method for your raw files, will you ?  Wink
Logged
madmanchan
Sr. Member
****
Offline Offline

Posts: 2101


« Reply #12 on: November 29, 2010, 08:27:51 AM »
ReplyReply

Yes, DNG is a documented image file format (basically an extension of TIFF) that can be used by anybody, but there have been revisions to it since its introduction. Just like there are multiple versions of JPEG, TIFF, MPEG, etc.

Yes, the DNG Converter will allow you to process a new raw image in an older version of ACR.

It is true that the public DNG SDK only contains a simple bilinear demosaic implementation, but the DNG Converter does not use this.

For operations that require a demosaic step (e.g., conversion to 3-channel RGB), DNG Converter uses the same demosaic algorithm as Camera Raw, assuming the same version. For example, DNG Converter 6.2 and Camera Raw 6.2 use the same demosaic algorithm. Similarly, DNG Converter 4.4 and Camera Raw 4.4 use the same (older) demosaic algorithm. Newer versions of DNG Converter offer more camera support, have bug fixes, and improved features over earlier versions. For this reason, I generally recommend using the latest available version of DNG Converter (currently 6.2, soon to be 6.3), regardless of which version of Camera Raw you are using.
Logged

sniper
Sr. Member
****
Offline Offline

Posts: 580


« Reply #13 on: November 29, 2010, 09:37:17 AM »
ReplyReply

Why does the DNG converter use a different method from the published? i thought the whole idea was to make it a standard.
Wayne
Logged
fanlynne
Newbie
*
Offline Offline

Posts: 6



WWW
« Reply #14 on: December 14, 2010, 11:00:44 PM »
ReplyReply

If I converted a bunch of Canon 7D CR2 files to DNG using DNG Converter 5.5, should I reconvert from the original raw file with 5.6? What is different about the files, since the raw data should remain unchanged?
I thought the advantage of using raw/DNG was that the file itself stayed intact and that, as raw processing algorithms get better over time, the data could be "crunched" in different ways to make the image better. I am getting a sense now that some of my DNG files created using older versions of the DNG Converter (I have been using DNG for several years now) are somehow inferior to those created using the latest version of the converter. Tongue
« Last Edit: December 14, 2010, 11:03:18 PM by fanlynne » Logged
Pages: [1]   Top of Page
Print
Jump to:  

Ad
Ad
Ad