In my last post, I said that "The final JPG image is not so good for "serious" photography. On reflection, I thought that it may have been a bit harsh, but today I spoke with an advanced amateur photographer. He mentioned that he is starting think about RAW after reviewing some images he took on a trip to Iceland a few years ago. His comment to me was that he's like to apply some processing to improve the results, but since he shot JPG's, there was not enough data to work with.
To understand what he meant, we have to understand that a RAW image file contains ALL of the data that the camera's sensor is capable of gathering. The image file is called RAW because it is unprocessed by the camera's on-board software. Camera manufacturers use different file extensions for their files: Nikon uses .NEF, Canon uses .CRW or .CR2 and Olympus uses .ORF. Although not compatible with each other, these files share the same attributes in that they contain image data, not pictures. To see what the sensor "saw" these files have to be processed (interpreted) by software such as Adobe Camera Raw, Aperture or Lightroom. The electronic process is analogous to "developing" film. When you shot an image on film, you knew it was there, but you did not expect to see it until the film was processed and you could review the "negatives". This is sort of the same, but using computers instead of chemicals.
The HUGE benefit to RAW is that once captured, you can change much of an image's settings such as white balance, exposure, colour saturation and contrast. And you apply changes to all or just a portion of the image. The COOL thing is that the actual file that came from your camera is NEVER affected. The changes are tracked in a "sidecar" file that keeps track of your edits and the software applies them when you view or print the image. For this reason, the edits are referred to as "non-destructive" and your original RAW file is never compressed.
So - why would you shoot in RAW? Because YOU have control over the final result, not the brilliant engineers who designed your camera hoping they can give you what you want. The next (last?) blog on the subject will deal with examples of what you can accomplish with RAW.