Aperture Users Network

Adobe’s Digital Negative file format (or DNG) was touted when it was announced by many as the holy grail of digital photography. In an article I wrote for Photo District News I glowed over the company’s promise that DNG would help unify the world of photography by providing a single unifying file format that everything could work with.

DNG hasn’t been as much of a global salvation as planned, but it is a very handy file format. The standard’s not quite as “open” as promised and not every imaging program can work with a DNG file. In Aperture 1.5 for example it was only possible to import a DNG file that belonged to a camera format that could already be converted. Handy if someone had sent you a DNG file from something like a D2X, not so handy if you were getting a file off of a non-supported Hasselblad back.

Aperture 2 has embraced the DNG file format and that’s big news for photographers for a few reasons. The most obvious reason is that it allows Aperture to work with a vastly greater range of images. If a file format’s not supported by Aperture but can be converted by Adobe DNG converter, it’s now fair game in Aperture. This is great for people with legacy images and files from DNG based cameras.

The less obvious part of this is that it means that issues about Apple’s speed of introducing raw conversions for new cameras is much less important than it was. (To be sure, we all want native raw conversions as soon as possible, that hasn’t changed.) As long as the Adobe DNG converter can handle the file format, so can Aperture.

Since Apple’s been historically slower than Adobe on raw conversion, this frees up the early-adopter photographer, who will no longer have to decide between waiting for a new camera to be supported in Aperture or jumping ship to keep their workflow going. Now it’s simply a matter of converting images into DNG and going from there.

Conversion Process

The first step in using a DNG image is to get an image into the DNG format. If the camera shoots into DNG, you’re already there, but if the camera doesn’t then just fire up the free Adobe DNG Converter and make some DNG files.

The easiest way to find the most recent DNG Converter is to head over to Adobe’s site’s Download page and type DNG into the search area. Obviously, you’ll want the Mac version. As of this writing though the DNG files were available at this URL.

http://www.adobe.com/support/downloa...form=Macintosh

The download will contain two files, the DNG converter and a Camera-Raw Plug-in. The plug-in file is only necessary if you’re using CS3 and want to update to that.

Copy the DNG Converter to your applications folder and launch it.





The converter is relatively straight forward, with just four panes used to convert files. The first panel specifies which folder contains the files you want to convert from while the second pane selects the location to export the converted files to.

Bonus Tip: - You can use the DNG converter as an import tool, using the first pane to select a group of images on a CompactFlash or other storage card (or even in a camera that’s connected to your machine) and move them to a folder on your desktop by picking the card in the first pane and your drive on the second. [/b]

If you’d like to change the name of your images while converting them, use the third pane to specific a new naming convention. This application’s actually very handy when it comes to file naming schemes. In this case we’ve got it set to use the original document name and append a two digit serial number, but you could just as easily have it add time, text or date information into any of the fields.

Conversion Steps

The fourth pane is the key for getting your images into Aperture. There are several types of DNG file, mosaic and linear. Aperture needs mosaic files, so before you convert be sure to click the “Change Preferences” button.



There’s only one key preference needed to import your images to Aperture, the others are optional settings, but we recommend some. The first choice, “Preview” sets the size of the DNG preview image. Since Aperture can be set via preferences to display the preview embedded in the original image, choosing a large preview will improve the quality of the shot in Aperture in Quick Preview mode. However, it’ll take longer to process the file than if a medium side preview or no preview are selected.

Compression is also optional, however it (by definition) makes the file smaller. It also take longer to compress an image than it takes to convert a file without compression, so this can be set off for better performance.

The “Image Conversion” setting is the one preference that must be set correctly for Aperture to process the images—the method has to be set to “Preserve Raw Image”. This is called a mosaic DNG, and it contains the most data possible. It also makes it possible for Aperture to read the file, and to process the file using either the DNG converter or Aperture’s own raw engine, if possible.

The final choice is for the “Original Raw File” to be embedded in the DNG or not. This isn’t required, and it makes the file size larger, but it does allow the file to be extracted from the DNG in the future, should you need to. This would mostly allow photographers to, say, remove the .NEF from inside a DNG should DNG end as a supported file type. Again, it’s not necessary for Aperture to process the file.

Once you set these preferences there’s no need to go back into this portion of the Adobe DNG converter, and you’re ready to convert.

Conversion Process

Back in the main pane of the Adobe DNG Converter simply hit the “Convert” button and the program will begin creating DNG files. One thing to remember is that if you select anything besides “Save in Same Location” for the destination then the converter will always use the location you last set. So if you converted a folder of images and sent them to a temporary location to import from, the next conversion will go to the same place.

If you select “Save in Same Location” the program will put the DNG files into the same folder as the source files. (Don’t do this if you used our tip above for copying images from a CF card using the converter or the conversion will be extremely slow and will fail of your card is full.) That makes it more convenient to find the files, but you’ll have to manually drag your files onto Aperture to import them because using the regular Import tool will bring in both the (supported) DNG and the original (non supported) file.

That’s why we like to convert the images into a new location, and remember to clear out the folder between imports (in fact we made a handy Automator script that removes all the files in a folder with the double-click of an icon).

Once files are imported as DNG, a new option will be available in the “RAW Fine Tuning” section of the Adjustment inspector, which indicates that the file is being adjusted using the DNG decoder. This box reads “2.0 DNG” and changes to the image using the 2.0 DNG converter are made based on the DNG specification of the file.



If the DNG is for a file that Aperture can already support (or if the file is viewed after support for a format is added) there will be the standard choice of processing the image using the Aperture 2.0 conversion, by selecting “2.0” from the drop down menu. The idea here is that the specific Aperture conversion does a better camera-specific job than the generic DNG does. (So in short, use the 2.0 choice if it’s available, rather than the 2.0 DNG, which is only the default choice if the camera format is not supported by Aperture directly.)

The new DNG support opens up worlds of possibility for Aperture users, and in fact we’ve recently imported thousands of images from previous test shots from cameras like the Kodak DCS Pro SLR/n and several Hasselblad backs. It’s great to be able to work with these legacy files using the powerful adjustment tools in Aperture.

It’s also great to know that going forward it’s going to be possible to take advantage of DNG converted files for cameras that are still under development from Apple. We know they put a lot of effort into the raw conversions (especially when it comes to the “RAW Fine Tuning” settings, which is one of the reasons their converters take longer to release than Adobe’s, but now it’ll be possible to keep working with new (and legacy) files as long as they’re supported by the DNG converter.