Raw to DNG conversion and vice versa

[chinmaya]

Currently I edit all my images as raw, export them to high-quality JPEG.

And then add metadata (IPTC) into JPEG to save all keywords, location,

copyrights etc.

 

But I would prefer to do it on Raw. I believe CR2 does not support

embedding IPTC info. So I guess best option for me would be to

use DNG?

 

I have done bit research, I believe once I convert CR2 to DNG, there is no

way I could get back CR2, is that correct?

 

If I convert to DNG then I would not be able to Digital Photo Professional that

came free with my Camera. So I will be forced to buy a software which support

DNG editing.

 

So my question is

 

1. Is there way I could retrieve CR2 back from DNG

 

2. Is there a way I could add meta-data to CR2, which is not dependent on the

photo-manager software that write the data.

 

 

I am guessing one option would be to saving all my meta-data in XMP

and keep it next to CR2 and zip them into one file.

[marc_rochkind]

1. You can get the original CR2 "back" in the sense that there's an option with DNG Converter to embed it and later extract it. But, as far as I know, there's no way to convert the DNG with your edits to the equivalent CR2. Indeed, I don't know that that even makes sense theoretically.

 

2. Adobe apps "add" metadata to native raw formats by putting a sidecar file (*.XMP) next to them to hold the metadata. They do not write into the native raw. Other apps are not so limited, but I don't know the details.

[ellis_vener_photography]

1."and then add metadata (IPTC) into JPEG to save all keywords, location, copyrights

etc. But I would prefer to do it on Raw. "

 

You can do it in either Bridge or better, Adobe Photoshop Lightroom.

 

2.)" I have done bit research, I believe once I convert CR2 to DNG, there is no way I

could get back CR2, is that correct?"

 

That is correct. But DNG is an open source raw format.

[godfrey]

DNG is not open source. It is a publicly disclosed file format specification, requiring

only the signature on a license and no fees to acquire the specification and/or produce

products based upon it.

 

As above, either edit metadata in Bridge or Lightroom and save the metadata out to the

files as .XMP sidecar files, or convert the CR2 files to DNG. You can embed the .CR2

into the DNG files to allow retrieval of the original files. The metadata will still be in the

DNG file, which (with Lightroom) could be captured and reapplied to the .CR2 (again

creating a .XMP sidecar).

 

I convert all RAW files to .DNG and do my image management and editing in Lightroom

or Photoshop/Bridge/Camera Raw. It works fine, I've never had to retrieve a native

RAW file (they're archived on a separate volume, just in case).

 

Godfrey

[Richard Williams]

Does Canon's own software allow you to edit CR2 metadata directly? - might be worth a look.

 

ExifTool can write metadata to CR2s The basic program runs from the command line, but there are various 3rd party GUIs:

 

http://www.sno.phy.queensu.ca/~phil/exiftool

 

I'm pretty sure Photo Mechanic can also do this:

 

http://www.camerabits.com/site/index.html

[Ed_Ingold]

Let us clear up a few misconceptions.

 

When you "convert" raw files to DNG, a new file is created. The original RAW file is not changed. You cannot effectively convert a DNG file to a RAW file in any way (you could fake the file extension).

 

The advantage to DNG files is that the converter is free and up to date, and many programs will edit ENG files even if they will not edit the source RAW files.

 

Some metafile data is copied from the RAW file, others are not.