Problems of using 2 RAW converters in series?

[lllusion]

What problems can be introduced by using 2 raw converters, one for demosaicing and the other for further adjustments?

[Hermie]

What problems can be introduced by using 2 raw converters, one for demosaicing and the other for further adjustments?
[{POST_SNAPBACK}][/a]

First off, you've got to make a distinction between a raw convertor and an editor.
I like the way Uwe from DOP describes is here:
[a href=\"http://www.outbackphoto.com/artofraw/raw_26/essay.html]http://www.outbackphoto.com/artofraw/raw_26/essay.html[/url]
See the 1st part where he writes about Image editor, raw convertor and photo editor.

Hermie

[lllusion]

First off, you've got to make a distinction between a raw convertor and an editor.
I like the way Uwe from DOP describes is here:
http://www.outbackphoto.com/artofraw/raw_26/essay.html
See the 1st part where he writes about Image editor, raw convertor and photo editor.

Ok, and your point, in reference to my question was? I'm not trying to be smart, just trying to understand how this helped answer my question.

Perhaps I should have given some more information.

I'm looking to use DxO for demosaicing because of its great distortion correction, as well as its noise reduction and anti-softness (capture sharpening) features. Results are saved as a DNG. From there an import to LR occurs and all further 'raw' processing occurs in the Dev. module.

Just for reference to the OutbackPhoto link:
Both DxO and LR are raw converters because of their demosaicing ability. According to the definitions in the article, LR would also be a photo editor because it can take a "photo from the RAW/JPEG/TIFF camera (or scans) to the final printable version". Although LR certainly does not have the range of editing tools that LightZone has.

So, my original question stands. What problems and errors can be introduced by demosaicing with one and adjusting with the other?

TIA.

[Hermie]

I didn't mean to sound patronizing, but as I didn't know your intended workflow (explained in your second posting), I wanted to make sure that you didn't mix up things.

As you are saving to DNG and thus to RAW, the effect should theoretically be zero.

Hermie

[lllusion]

I didn't mean to sound patronizing, but as I didn't know your intended workflow (explained in your second posting), I wanted to make sure that you didn't mix up things.

Thank you. I didn't think you meant to be condescending, especially as I realized that my initial post was incomplete without some background information. Thank you for helping clarify the different processes.

As you are saving to DNG and thus to RAW, the effect should theoretically be zero.

Yes, theoretically, but I'm wondering if there is some technical information that proves this incorrect. DxO outputs a Linear DNG not a Raw DNG. Can this affects quality and processing in, for example, LR? (I've asked the question in the Adobe Labs forum and, as yet, have not had any response.)

[Hermie]

Yes, theoretically, but I'm wondering if there is some technical information that proves this incorrect. DxO outputs a Linear DNG not a Raw DNG. Can this affects quality and processing in, for example, LR? (I've asked the question in the Adobe Labs forum and, as yet, have not had any response.)
[{POST_SNAPBACK}][/a]

Interesting, did you see this link on linear DNG [a href=\"http://www.barry.pearson.name/articles/dng/linear.htm]http://www.barry.pearson.name/articles/dng/linear.htm[/url]

and Bruce Fraser's comment on linear DNG:
"Bruce Fraser sent the following comment regarding Linear DNG: “The only reason to use Linear DNG is to feed the file to a DNG reader that can’t understand the particular flavor of DNG that DNG Converter creates for the specific camera, or to act as an interchange format-e.g., lens correx with DxO can write out a linear DNG that ACR can read. This is typically NOT an option people want, not because of size considerations, but because it’s no longer really raw-it’s half-baked. All the operations that take place during demosaicing are set in stone and can’t be redone.” see http://www.photoshopnews.com/2005/05/23/dng-workflow-part-i/

[lllusion]

Exactly, it's partly because of those articles/websites that my questioning has begun. I've submitted a request to DxO to create a PS plug-in for noise, anti-softness, and distortion correction so that demosaicing and all other raw developing can be done by LR.

Certainly it's best to let LR have access to the original raw bits, but what happens if they don't? My testing (to see if I can spot any decrease in quality) is not complete but I'd sure love some technical data along the way. With that in mind, does anyone know what demosaicing algorithms DxO and LR use?

[John Sheehy]

DxO outputs a Linear DNG not a Raw DNG. Can this affects quality and processing in, for example, LR? (I've asked the question in the Adobe Labs forum and, as yet, have not had any response.)
[a href=\"index.php?act=findpost&pid=79916\"][{POST_SNAPBACK}][/a]

The fact that a DNG is output suggests to me that demosaicing is done (or something like it, if the Bayer-patterned data is shifted with sub-pixel precision before creating three full color-planes) already by DxO, so the RAW converter doesn't have to do that part.  The only problem I can think of is if the data is white-balanced in DxO, it may not be properly white-balanced in a converter.  Data that is already equally sensitive in the three color channels can not be white-balanced in some converters (ACR had this problem, at least in older versions).  I doubt that DxO would output DNGs that weren't usable, though.

Bottom line - why don't you try it?

[lllusion]

The fact that a DNG is output suggests to me that demosaicing is done (or something like it, if the Bayer-patterned data is shifted with sub-pixel precision before creating three full color-planes) already by DxO, so the RAW converter doesn't have to do that part.  The only problem I can think of is if the data is white-balanced in DxO, it may not be properly white-balanced in a converter.  Data that is already equally sensitive in the three color channels can not be white-balanced in some converters (ACR had this problem, at least in older versions).  I doubt that DxO would output DNGs that weren't usable, though.

Bottom line - why don't you try it?
[a href=\"index.php?act=findpost&pid=79928\"][{POST_SNAPBACK}][/a]

I have tried it, and it works. Demosaicing is definitely done since the output is a Linear DNG and not a Raw DNG. ACR inputs the file just fine and all controls work, including WB. The only funkiness I've seen is that ACR sometimes displays a pink overlay in some of the highlights. DxO's highlight recovery may be the root cause here. But this highlight overlay display doesn't seem to affect the image once in PS.

I still need to complete a series of tests to check for quality. But these results are only subjective (and since it's art then that's often what matters most). However, it doesn't supercede the interest in any technical information/data that's available, and which would be more objective, as to technical problems that can arise that would lead to a decrease in image quality.