What is Camera Raw?

When you shoot in Raw, the files your digital camera produces are unprocessed, uncompressed sensor data, as captured by your camera.

Tonal Information

A typical Raw file has at least 12 bits of tonal information per pixel - with newer cameras having up to 14 bits of tonal information per pixel. Jpeg files only have 8 bits of tonal information per pixel. When you shoot in Jpeg you are letting your camera’s built in Raw converter decide which information to squeeze into the available 8 bits of tonal information. This means that your camera throws away anything from 4 - 6 bits of channel data for every pixel, not only leaving you with less data to work with when you open it up in a photo editor, but also resulting in less tonal range in the final image, and in some cases this could mean inaccurate skin tones.

Lossless Format

Raw is a lossless (uncompressed) format, whereas Jpeg is a compressed format.

When you edit a raw file you don’t actually make changes to the raw file - instead changes are made to a sidecar “XMP” file which includes all the adjustments you made.

Changes are never made in the raw file which means that the raw file always remains unchanged.

An “XMP” file is a metadata file which can be edited with any text editor. Each metadata file has the same name as the original raw file, but has an .xmp extension. Working with raw files

There are different raw processors available - with Adobe Camera Raw being the most popular. Typically the software that comes with your camera allows you to edit files and will use it’s own raw converter. Apple’s aperture also has it’s own raw converter.

Adobe Lightroom, Adobe Elements, Adobe Photoshop and Adobe Bridge all use the same Adobe Camera Raw converter, so regardless of which one of these packages you use, you will be using the same full blown Adobe Camera Raw converter.

If you open a raw file from Adobe Bridge, Elements, Lightroom or Photoshop, the Adobe Camera Raw converter will automatically open.

For the purposes of this site we will use Adobe Camera Raw in all examples as that is probably the most popular and up to date raw converter available.

Advantages of raw

More tonal information to work with : minimum of 12 bits of data vs 8 bits of data.
More leeway to correct mistakes after the fact.
Ability to change color space, white balance and color temperature after the fact without affecting image quality.
Lossless format that can be edited non destructively.

Disadvantages of raw

File sizes are bigger than jpeg. This means that the files are slower to open, takes longer to transfer, your hard drive runs out of space quicker, your backups are bigger, and when you are shooting motor drive sequences your buffer will fill up sooner.
Takes longer to edit files : jpegs are ready to view and print straight out of the camera whereas raw files must be converted first.