The Digital Domain: Shooting in Raw Format
We saw in the section on File Formats that JPEG is the most popular format for digital cameras. However all DSLRs (and some superzoom / bridge cameras) have another format called RAW, and most professionals and enthusiasts choose to shoot in this. Technically it should not be written in all capitals as it is a term used to describe the storage of the raw data from the image sensor, but we prefer to write it that way when referring to the actual image file (i.e. when using it as a noun rather than an adjective).
So why would you use RAW over JPEG? The following table illustrates some of the advantages and disadvantages of each. The advantages of JPEG are generally to do with convenience Ė whereas RAW files focus on creative control and image quality. If you have read this far, then we suspect the latter might be of more importance to you and so our advice would always be to shoot in RAW.
|Small file sizes (more pictures on a memory card)
||Larger files (less pictures on the memory card)|
|Viewable in all image software
||Usually needs to be converted to a JPEG or another format before it can be open up in most image software (therefore an extra step is always involved)|
|Image processing such as white balance correction, sharpning and noise reduction are done in camera before image is stored
||No image processing is done by the camera - this is done by the RAW converter on the PC under your complete control.|
|Less creative as decisions made by the camera in creating the JPEG are fixed
||More creative - in converting from RAW you can apply the cameras suggested settings, or override this and create something you find more pleasing.|
|Burnt out highlights can never be recovered.
||The exposure can be adjusted so that areas of burnt out highlights can, up to a point, be corrected.|
|If you select to shoot in black and white, the colour information is lost completely
||If you select to shoot in black and white, you will see the black and white image to help in composition, but the RAW file will contain the full colour data. You therefore retain full control in the black & white conversion process on the PC.|
|Smaller files means you can take more shots in continuous shooting mode before the camera has to write the data to the memory card.
||Larger files, so the internal memory buffer will fill up quicker.|
|Lossy compression - image data is thrown away in order to create smaller files. Each time you save a JPEG the image quality degrades further.
||Lossless format - no data is discarded when the image is saved.|
|8-bit colour quality (256 levels for each primary colour)
||Often 12-bit or 14-bit (giving 4,096 or 16,384 different levels for each primary colour). Can store more subtle colour variations|
|A standard that youíll still be able to view in 20 years time
||Format constantly changing Ė different between manufacturers. NOT suitable for long term archive of images.|
In RAW mode, the camera stores all the digital data from the sensor. Some cameras will apply compression to the RAW file although this is always a lossless compression (no image data is thrown away). It is the data the camera's image processor uses to create the JPEG file, but by leaving it in RAW format, you can more precisely control the conversion to JPEG (or any other format) on your computer, and even correct some faults in the image that would be considerably more difficult if the conversion to JPEG has already taken place in the camera.
Cameras that have the option to shoot in RAW format also usually come with the appropriate software to carry out the conversion - however leading packages like Photoshop also include RAW conversion as standard - Adobe's being called "Adobe Camera Raw".
Picture by Colin - shows an image loaded into Adobe Camera Raw. Note how properties such as colour temperature which are fixed in JPEG files can be easily changed in RAW format files.
Donít Archive in RAW
Despite all its advantages, the biggest problem with RAW is that it is camera make and model specific. The RAW files from a Canon EOS 350D and completely incompatible with RAW files from a Nikon D80. In fact they are incompatible with files from other Canon models.
This means that once your camera is discontinued there is a good chance that software support for its RAW file format will start to disappear. If you backup all your RAW images to CD then you may get a shock in 10 years when you come to look at them and find you canít open them in any software you have, and the old conversion software you have wonít run on the current version of Microsoft Windows.
Any images that you decide to keep should be converted to a standard format such as JPEG or TIFF which will still be around in 10 years time. Most DSLR cameras come with RAW conversion software that can process whole folders of image in one go so this is not as big a job as you might think.
Digital Negative Format (DNG)
In 2004 Adobe Systems announced the Digital Negative file format in an attempt to create a unifying RAW file format. Despite allowing anyone to download their free Adobe DNG convertor, the format has to date not been a great success. The only mainstream DSLR manufacturers to support this format in camera are Pentax and Samsung. It is also found on specialist cameras like Hasselblad and Leica.
Despite this it is probably a safer bet to use DNG for long term storage than Nikonís or Canonís RAW format. Personally we would advise to use high quality JPEG or TIFF to ensure long term compatibility (shoot in RAW and batch convert rather than shooting in JPEG).
This is a site about photography so I'm sure you are expecting to see plenty of pictures.
For now, why not take a peek at the flickr galleries belonging to the two authors of this site.
Colin's Flickr Page
Phil's Flickr Page
"My work is nothing more than a visual diary of a very long walk."
- Andrew Stark