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Camera Raw

Camera Raw?

Modern digital cameras typically produce two types of files - Jpeg files and camera RAW files. Some can also output Tiff files.

Camera raw files are becoming an increasingly popular format in digital photography workflows because they offer greater creative control over images.

What are the differences, pros and cons between the two formats? Read on.

First Jpegs.

The advantage of using Jpeg files over RAW files is that they have been around for years and can be read by just about any image editing program and used immediately in almost any other programme that an incorporate images. Secondly, their file size is much smaller (they are created by using "lossy" compression which removes picture information to make a smaller file) and therefore more manageable making them suitable for emailing etc with minimal hassle.

Jpeg files are therefore convenient and don't necessarily require any editing, which is why they have such a great appeal to those without the time, inclination or skills to edit their images.

When shooting a Jpeg image the camera uses its own built-in raw converter. This converter throws away a large amount of the captured data whilst interpreting all of the in-camera settings for colour balance, colour temperature, sharpening and so forth within the file in a way that will hopefully do the image justice. Unfortunately during this process we have essentially no control over what gets discarded or how certain things are interpreted and can therefore lose a large range of information.

Raw

Apart from a Camera RAW file typically containing at least 12 bits, or 4096 shades, of tonal information per pixel as unprocessed data captured directly from the cameras image sensor, the the real advantage of using a RAW format file is that it has received almost no processing by the camera. No artificial sharpening or white balance will have been applied. This means that when working on a RAW file in an image manipulation program you are starting out with a much higher quality original than with a JPG file and have much greater flexibility in applying corrections and adjustments without significantly degrading the final image quality. Shooting Jpeg is a bit like shooting instant polaroid film whilst shooting Raw is more like shooting negative film.

With Jpeg, as with polaroid film, you need to get everything right in-camera as there is little you can change later.

Shooting raw provides considerable latitude in determining the final tonal rendition, and offers freedom in interpreting the colour balance and saturation. In addition, Raw also lets you control detail rendition - noise reduction and sharpening.

The Catch (apart from size)?

Raw files are only a few years old unlike Jpeg which have become an industry and web standard. Raw files are, generally, a proprietary format and are unique to each camera manufacturer and sometimes even to each camera model. There are many different types of raw files around, the specifications for which are not publicly available.
This means that a special program to "decode" the files is required. Camera manufacturers usually provide special software for decoding their own Raw files. However, the UFRaw add-on for Gimp as well as the newer versions of Adobe Photoshop can open the majority of Raw file formats.

What does it all mean?

The use of these proprietary Raw files as a long-term archive solution carries risk, and sharing these files across complex workflows is even more challenging.

Is there a Solution?

Thankfully, yes. The Digital Negative (DNG) is a publicly available archival format for Raw files generated by digital cameras. By addressing the lack of an accepted standard for Raw files created by individual camera models, DNG helps ensure that photographers will be able to access their files in the future. By working with these "digital negatives" you can acheive the results you want with greater artistic control and flexibility while still maintaining the original "raw" files. The DNG is available at no charge making it more accessible and, ultimately, a safer choice for long-term archival purposes.

For information on the Free DNG converter see:
http://www.adobe.com/products/dng/

http://www.openraw.org/ group advocating the open documentation of digital camera raw files.

To find more information about the UFRaw utility see:
http://ufraw.sourceforge.net/