Section 4.1. Save to DNG


4.1. Save to DNG

One scary thing about shooting RAW files is that very few cameras shoot RAW in what I have reason to believe will become a long-lasting and universal format: Adobe's open source digital negative (DNG). There are several reasons for this, such as the branding ego of various camera manufacturers. The danger is that we know ultimately all these proprietary formats will drop out of existence, either because of technological improvements, marketing considerations, or mergers and dissolutions of manufacturers. At that point, you have your files in a format that is no longer supported. So be smart: as soon as you download your images from the camera and have added the appropriate metadata (see Chapter 1), use Adobe's DNG Converter to convert all your proprietary files to DNG. I save these files in a subfolder. I also save them in a folder called "DNG backup." As soon as there are enough conversion files in the DNG backup folder to fill a DVD, I do just that. If you have a new camera that sports a new RAW format, make sure you've loaded the latest version of the DNG Converter from the Adobe site: http://www.adobe.com/products/dng/main.html.

The DNG converter is very quick and easy to use. Of course it's annoying (and easy to forget) to perform any routine that's new to your work habits, but you'll be very glad you did. Even if you think your particular iteration of your camera maker's proprietary RAW format will never disappear, one more backup is just plain good insurance.

The DNG Converter can translate the entire download folder at once and gives you the option to save the DNG files to separate folders. If you choose to save to .dng, I recommend that you check only the Compressed DNG option (the compression is lossless, so why not save drive space?) and choose Medium as your JPEG preview size. You can see the "Save to DNG" dialog in Figure 4-1.

Figure 4-1. The DNG Converter dialog.

Here's the step-by-step process to save a DNG file:

  1. Download the converter and create a shortcut for your desktop.

  2. Download the files from a shoot, put them into the same folder, and follow the naming conventions suggested in the "Renaming Individual Files" section in Chapter 3.

  3. Go to your desktop and click the Adobe Digital Negative Converter icon. The dialog in Figure 4-1 will appear.

  4. Click the Select Folder button to choose the folder of files you want to convert. If you've (for some strange reason) already decided to create subfolders of files in other formats or put your rejects into a subfolder, you'll want to uncheck the "Include images contained within subfolders" checkbox.

  5. Click the Select Folder button. Go to your parent folder for this shoot and create a subfolder with DNG Backup as the prefix and the name you've given the parent folder. So the folder name will be something like DNG Backup Smith Wdng.

  6. Leave the third section of the dialog box untouched (you have already named your files, right?) so that it uses the current filenames with .dng added.

  7. Stick with the preferences shown in Figure 4-1.

The rest all happens on its own, as if by magic.

If you forget to convert your camera's RAW files to DNG as soon as you download them, you can also save them to DNG with the Camera Raw Save button (but I don't recommend it). This also works if you have opened multiple files. Just complete the dialog in Figure 4-2 as shown.

Figure 4-2. Fill out the Save to DNG dialog as shown but be sure to use a category name that's appropriate to the image.

Camera Raw has many major advantages:


Nondestructive editing

RAW files are read-only. Any image adjustment you make in Camera Raw can be deleted or readjusted at any time without affecting the information your camera originally recorded. The edits you create in any RAW processor, including Photoshop CS2's Camera Raw, are only recorded as metadata instructions as to how the picture should appear when it's viewed or edited in an image processor, such as Photoshop CS2. The actual pixel data remains unchanged. The only way you can destroy your original image would be to delete the file without backing it up. Hopefully, you always back up your images to DVD immediately after downloading them to the computer. This means that you can always recover when you need to create a different interpretation of the data.


No need for color balance adjustment in camera

Camera Raw lets you visually change the overall color temperature of your image, so you can choose not only from daylight and tungsten but also from virtually every color temperature and tint in between. Of course, if you do set color balance in your camera, you're likely to see an image that's closer to what you had in mind when you first previewed that image in Camera Raw, so there will be a little less work to do.


Five to seven f-stops of exposure latitude

Yes, you heard that right. Even if your image was shot two full stops over or under the "ideal" exposure, there's an excellent chance that you can rescue it by dragging a few slider handlesno one will ever know. How much latitude a given camera's RAW files actually contain will depend on how many bits of data were actually recorded. Only a few very high-end cameras actually record more than 12 bits of data in the 16 bits that are available to RAW files. By the way, just because you can be sloppy with your exposures doesn't mean you should be. If you expose properly, you can use that same latitude to extend the dynamic (brightness) range of your images so that you can produce highly detailed photos that closely approximate the range of brightness seen by the human eye. Figure 4-3 shows the same image adjusted to three different "exposures."

Figure 4-3. The same image adjusted (from left to right) to minimum exposure, Auto exposure, and maximum exposure. Note that none of these renditions contains significant "blocked" data.


Immense time-savings due to highly automated processing of multiple files

Photoshop CS2 Camera Raw actually provides you with the means to adjust a whole series of images at the same time (see Figure 4-4).

Figure 4-4. Camera Raw with a series of images from a portrait shoot that are all open at the same time. In this instance, all have been selected and Synchronize was turned on so that any adjustment affects all the selected images equally.


Easy elimination of "losers"

Camera Raw provides you with the means to quickly review a whole series of images at 100 percent magnification so that you can eliminate images that are slightly out of focus or slightly motion-blurred.


Ability to archive your RAW files to a nonproprietary format

Adobe has created a RAW file formatDNGand made it available to all software publishers and camera makers. So, long after technology and changes in the industry have made the proprietary format your camera shoots obsolete, DNG format is likely to remain a standard.


Built into Photoshop CS and all later versions

You don't have to use your camera's supplied (and typically awkward or underpowered) program to render your RAW files. True, some proprietary and third-party RAW software (notably Phase One's Capture One and Pixmantec's Raw Shooter Premium) is even faster and more powerful than Camera Raw. However, the Camera Raw version in CS2 does a lot to narrow the gap, and you don't have to spend extra to get it.


Ability to open files in Photoshop in 16-bit mode

To put it another way, you can keep every bit of the data that exists after you've adjusted your image in Camera Raw. So if you want to make even more adjustments in Photoshop for dramatic effect, you're far less likely to see posterization in your images as a result. Posterization occurs when the adjustments you make "stretch" two specific levels of brightness and there isn't enough data in between to bridge the two new levels of brightness (see Figure 4-5). It's admittedly a bit hard to visualize what this means, but I'm sure you've looked at the Histogram for an 8-bit image after it's been adjusted and seen a diagram that looks like Figure 4-5.

Figure 4-5. Posterization indicated by a "combed" Histogram (right) and the histogram for the same image when the adjustment is made from a 16-bit file (left). The space between the "fingers" in the Histogram is represented in the image as being of uniform color and brightness.


Added Curve control

With CS2, there's a tab in Camera Raw that lets you adjust contrast in specific brightness ranges within a given image, just as you can in Photoshop (see Figure 4-6). This capability is especially valuable to make a better first proof of your images for client and subject approval. The Curve dialog is a simplified version of the one in Photoshop. (Before using it, you should first make your image look as good as possible by using the settings in the Adjust tab.)

Figure 4-6. The Camera Raw Curve tab.


Auto adjustments option

Wedding and sports photographers often argue that shooting in RAW significantly extends processing time, making it difficult to respond to the immediate turnaround demanded by their publications and clients. Camera Raw now attempts to answer that objection by defaulting to "smart" Auto adjustments for Exposure, Shadows, Brightness, and Contrast. As a result of Auto settings, you have a good or better chance of having a publishable image right out of the camera as if you'd shot JPEGs.




Digital Photography(c) Expert Techniques
Digital Photography Expert Techniques
ISBN: 0596526903
EAN: 2147483647
Year: 2004
Pages: 124
Authors: Ken Milburn

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