The Raw photography facts revealed

In the past I have discussed the merits of shooting and processing camera Raw images. Since then, I’ve left my camera’s format setting permanently on Raw, only shooting jpegs with my Canon Ixus.

The falling cost of digital SLRs and the trend for including Raw as an option on compact cameras such as the Canon Powershot S60 and Fujifilm Finepix F710 means most people with a good-quality digital camera can now shoot Raw.

But many people aren’t aware of the benefits Raw files provide, and are put off by the need for additional post-processing using software provided by the camera manufacturer or a third-party application such as Adobe Camera Raw .

While in many situations you might be hard pressed to tell the difference between a high-quality camera-processed jpeg and a post-processed Raw file, shooting Raw can enable you to squeeze every drop of potential from your shots and, in some circumstances, can make the difference between a useable shot and a write-off.

I’m not going to provide an in-depth technical explanation of Raw formats here; instead, I’ll concentrate on the practical side of shooting and processing Raw files to obtain the best possible results.

Drawbacks of shooting Raw
Possibly the biggest problem with Raw files is that, because they are proprietary, no two formats are the same.

Not only is Canon’s format different from that of Nikon, Konika Minolta, Olympus and everyone else, but Raw formats also vary from model to model so there’s no guarantee the Raw images from, say, Canon’s new EOS 30D are the same as those from the 20D.

You need to make sure that any Raw conversion software or image-editing application you buy supports Raw images from your camera model.

One way around this is to convert all your images to Adobe’s open dng raw format. For more info on dng go to the Adobe website.

As Raw files are uncompressed they tend to be quite large – around 8MB compared with 2.5MB for a high-quality jpeg from an 8megapixel camera. So they take longer to write to the media card and you get fewer images on a card compared with jpegs.

Time to write to the card will only be an issue if you’re shooting continuous frames. For example, the Canon EOS 20D can shoot high-quality jpegs at five frames per second (fps) for a maximum burst of 20 frames before its buffer is filled, but shooting Raw limits the maximum burst rate to six images.

It also takes longer to transfer your Raw files from the media card to your hard drive.

Once this is done you’ll need to convert them to a conventional file format such as jpeg, tif or psd using the software supplied with your camera, or a third-party application such as Adobe Camera Raw, Pixmantec Rawshooter or Corel Paint Shop Pro .

This is both a drawback – as it adds another stage to your workflow – and a huge advantage, because you, rather than your camera, are in control of the process.

In a nutshell, what the camera does when it produces a jpeg from your camera’s sensor data is convert the greyscale data into RGB pixel values – a process known as demosaicing – and apply white balance, saturation, sharpening and any other processes as defined by the camera settings.

By taking control of these processes and treating each image individually rather than applying a catch-all set of functions, you can produce a marked increase in image quality.

Raw image processing is about more than just tweaking saturation and sharpening though. Most digital cameras capture 12bits of information per pixel which is downsampled to 8bits in the camera when you use a jpeg setting.

By shooting Raw you can retain all that data or decide on the best method for conversion. In either case, the result will be a robust file, with more tonal information that can undergo adjustment in your image-editing application without noticeable degradation such as posterisation.