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Old Mar 6, 2007, 7:47 AM   #1
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Downloaded lightroom for a few days trail, like it so far but would like to know how to preserve the edited settings of canon 20D raw files?

Open 20D CR2 raw files in lightroom, do some edit, export as either tiff or jepg. - ok

Problem is once I remove those raw files from lightroom, the next time I import it back to lightroom again, all the previous settings/edit was gone! How can I save those setting in that raw files?

Some experts here can please help me out, thanks.

Julian


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Old Mar 6, 2007, 7:55 AM   #2
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The raw files are not being edited. So, there are no changes in them to be saved.

Editors that let you work on raw files and keep the changes you made are storing those changes in a separate file that's proprietary to a raw convertor. Basically, they modify the preview image you see in the converter with those changes, not the actual raw file itself.

If you want to make changes and see them in another editor, you need to use another file format (so that you're actually converting the raw file into a viewable/editable image first).

In addition, the algorithms being used to convert a raw image into a viewable image format differ greatly between converters (remember, a raw file has not been demosaiced into a usable format yet, and information from multiple photosites has to be interpolated in order to get red, green and blue stored for each pixel).

Even if there was a way to make changes to the raw file that you could migrate between converters, you wouldn't want to modify your originals (since you could easily ruin them if you made a mistake).

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Old Mar 7, 2007, 1:04 PM   #3
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Convert your RAW files to DNG Raw.
You can do this in Lightroom, but I prefer to use the Adobe DNG Converter before I Import them. It is a free download from the Adobe web site.

With DNG Raw, all the adjustments are kept in the file along with the original.
If you want the original you still have it and you still have the adjustments.
If you want to use the original, just use the Zero Preset in the Library.

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Old Mar 7, 2007, 1:10 PM   #4
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Tinkerer wrote:
Quote:
Convert your RAW files to DNG Raw.
I would still recommend that you keep your originals, even if you also want copies of your raw files in DNG format.

That's because byte offsets for some of the metadata can change during the conversion, so raw conversion tools that are optimized to read this data from a given camera model's files at specific byte offsets, may be clueless of how to decipher it once it's converted to another format, even with some that can convert a DNG file.

Personally, I never overwrite my orignals, with raw or jpeg files.


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Old Mar 7, 2007, 1:41 PM   #5
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Chris said he was using Canon, so no problem.
Adobe supply a list of camera types that are compatable.

The whole point of using DNG is to have a format that will be supported long after your camera ceases to exist.

What garauntee do you have that there will be software available to open your files in twenty years time.
Remember, it may not be you that is trying to open them.

Adobe have said they will always support the DNG format.

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Old Mar 7, 2007, 1:58 PM   #6
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Tinkerer wrote:
Quote:
Chris said he was using Canon, so no problem.
Adobe supply a list of camera types that are compatable."
No problem with what? Can existing tools that are able to read manufacturer specific makernotes able to do the same thing with dng files? Remember, Canon doesn't publish the specs for this metadata, and some tools look for it at specific byte offsets.

I've got great tools for reading lots of proprietary information from some raw files, even including things like focus points, all known camera settings, lens used down to the specific model and more.

Quote:
The whole point of using DNG is to have a format that will be supported long after your camera ceases to exist.

What garauntee do you have that there will be software available to open your files in twenty years time.

Remember, it may not be you that is trying to open them.

Well, since you asked... :-)

I keep my original raw files, along with a copy of Dave Coffin's dcraw.c (ANSI C source code for converting just about every camera ever made that can shoot in raw).

That way, I could always recompile the source later on any platform that has an ANSI Standard C compiler (and any major platform has a C compiler available). I recompile newer versions of it often anyway (on more than one platform). Windows is not the only game in town. ;-)

Unless the human species becomes very dumb (unlikely), you could still use it as documentation for recoding in a different language later, even if C as a language went away (also very unlikely). I'd put my money on Adobe going belly up before compilers are not available for C.

If you're not familiar with David Coffin, he has probably done more tor raw conversion than anyone alive, and some or all of his code is used in many raw converters. See the "Other Raw Photo Decoders" section of his web page here:

http://www.cybercom.net/~dcoffin/dcraw/

Here is what David Coffin had to say about DNG in December 2004 when I asked him about what he thought about DNG then (and he said that I could quote him):

David Coffin Wrote:
Quote:
"I think Adobe's DNG idea is well-intentioned, but suffers from two serious flaws:

First, why would camera makers want to change their raw formats? Compatibility leads to commoditization,and that leads to competition based on price alone. Great for consumers, terrible for producers.

Second, this format cannot anticipate innovations that haven't happened yet. When new sensors appear, the standard must be updated, along with the software that implements it.

There is only one way to guarantee that a digital archive will be readable in fifty years. For any non-text files, it must include decoding software as human-readable source code. If the decoder is written in a language other than C, it would be prudent to include an interpreter for that language, written in C.

Dcraw already fills this role. When the first DNG camera is available, dcraw.c will support it as one more raw format among many."

Now, David seems to have "warmed up" to DNG since then, and dcraw.c now supports DNG (he rewrote a lot of dcraw.c in order to support it).

Here are some comments from March 2005:


Quote:
Dcraw users,


After four months of work, dcraw 7.00 is available for download at http://cybercom.net/~dcoffin/dcraw/ . It's a major rewrite:


* Not only is Adobe DNG now supported, the entire codepath has been redesigned for it. Adobe's XYZ->CAM matrices allow color science to replace black magic, whether decoding DNG or the original raw files.

* The Foveon-related code has been completely rewritten to give realistic colors under all light sources. The license has changed. The new Foveon code is under the GPL license, so authors of closed-source applications may need to pay me to use it. The rest is under my old free-for-all license. See dcraw.c for details.

My future plans are:

* Adding support for SMaL-based thin cameras ( http://www.smalcamera.com/ ) Currently these cameras are completely useless without Windows.

* Improving camera white balance support, first for Canon, then Nikon, and maybe others.

Dave Coffin 3/9/2005

I'd keep the original raw files, along with a copy of dcraw.c, just in case support for a camera ever ended.

I also keep copies of popular open source programs that can read metadata from raw files (DigiKam and others), so that I know where to find maker notes, etc. in the raw files should the need ever arise (without the byte offsets changing by using a container liike DNG as a medium).

From my perspective, there is zero advantage to using dng as an archival format. The storage requirement advantage is "bogus" from my perspective (since there are a number of compression algorithms around that don't impact the original files after you decompress them (as opposed to byte offsets changing if you convert them to another format).

DNG is probably a safe bet (since dcraw.c can convert it to usable images, as can a number of other open source programs that use some or all of his code) for most uses if all else fails. But, I'd rather have the added security of support from programs designed to read the metadata at specific byte offsets in the original raw files from the camera manufacturer.

Could some of these be redesigned so that they know where to find and look for the metadata in the private data section of the DNG format? Sure. Are the developers going to do that? Only time will tell.


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Old Mar 7, 2007, 2:45 PM   #7
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Surely DCRaw is covering the same ground as DNGRaw.
It is offering a format that is independant of the camera manufacturer and does not rely any other format.

As time goes by it will get even more complex than at present.
As it needs to include a) The original file. b)The conversion software. c) Software that makes it independant of other O/Systems. c) The algorithm of every camera that exists, and will exist, the result will be a file very much larger than the original.
Bloated is a word that comes to mind.

What support will it have from the general public in fifty years time.
My money has to be on Adobe and their DNG standard.
They already have the support of Apple and Leica and several other organisations.

I have never used DCRaw, but it does have it's advocates.
The idea behind it is good.
It lacks the backing of a large organisation like Adobe and for that reason alone I feel that it's future is limited.

BTW. Thanks for the link.

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Old Mar 7, 2007, 3:17 PM   #8
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Bloated? :-)

The entire dcraw.c source code is only 220.4 KB

It will compile using an ANSI C compiler for just about any platform that has one (and that's just about any of them around that would be used as a desktop or server). It's not limited to AMD or Intel, Windows or Mac, etc. Almost any operating system has an ANSI C compiler available.

There is no platform specific code in it (so, no need for different versions for different operating systems). That's the beauty of keeping it ANSI Standard C. The compiler takes care of making the code platform specific.

For example, tt compiles to a .exe file of around 375KB if using a compiler for DOS. It's tight code.

It supports around 248 cameras at last count (far more than Adobe Camera Raw), and some or all of David's code is used by a number of both free and commercial raw converters.

Raw converter developers can use David's code as a model, then add their own GUI interface, features unique to their products, etc. It's ANSI Standard C, and it's free. So, David does the work, others take advantage of his good will.

Here's a partial list of products that use some or all of David's code to produce their own converters and editors to support raw files.
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