Photographers all know the basic difference between RAW files and jpgs. Put simply, RAW files are uncompressed and are more analogous to shooting with negative film, while jpgs are compressed and resemble shooting with transparencies. For those seeking a more technical explanation that is still easy to read, check out Bruce Fraser’s article (note: link to pdf) from Adobe that was recently promoted to the front page of digg.
When you shoot raw, the only on-camera settings that have an effect on the captured pixels are the ISO speed, the shutter speed, and the aperture setting. Everything else is under your control when you convert the raw file?you can reinterpret the white balance, the colorimetric rendering, the tonal response, and the detail response (sharpening and noise reduction) with a great deal of freedom.
The four page article also touches on the fact that there is no single type of raw file, but rather, there exist many proprietary formats from leading camera manufacturers (CRW, CR2, NEF, MRW, ORF). This alphabet soup of a list has been cause for concern in the photographic community and, as Shaminder Dulai recently wrote about, has spawned the OpenRAW initiative. This project calls for the “open documentation of information about the how the raw data is stored and the camera settings selected by the photographer.”
According to OpenRAW.org, the closed proprietary formats can only be opened by supported raw converters and some manufacturers have begun to encrypt the data in their newer RAW formats. Currently I cannot open RAW files from my Canon 1D Mark II N unless I use Canon’s Digital Photo Professional (the Adobe Camera RAW included in Photoshop CS cannot recognize the new .CR2 RAW format and I cannot afford to purchase CS2).
However, the real problem lies not in keeping up with newer formats, but in the discontinuation of support for older formats. OpenRAW.org lists as one of the four main problems associated with proprietary formats: “Increased probability that as time passes a RAW file will be unreadable or cannot be used to reproduce the photographer’s original interpretation.”
Though not dealing with RAW files, the San Jose State photojournalism program has experienced this problem when photographers check out and use the old Canon D2000. Professor Dennis Dunleavy addressed this problem in his blog in March of last year:
Even though these cameras still make decent pictures, the computer software that handles the TIFF files is quickly becoming ancient technology. In order for the newspaper to work with the images, we are required to work in the Mac OS 9 format, use special drivers in PhotoShop and download to a specific version of the PhotoMechanic image editing software.
The Spartan Daily has been forced to keep around older, obsolete machinery in order to have access to the D2000’s so that a photographer without his/her own digital camera may check one out for an assignment.
At the close of his article on understanding digital RAW capture, Fraser writes of one last benefit to shooting RAW. “If you shoot raw, you’ll be able to take advantage of future improvement in raw converters … Raw converters…have undergone radical improvements in the 10 years or so that color filter array cameras have been around, and there’s little reason to think that the next 10 years won’t see similar improvements.” I can only hope that the RAW files I shoot today will be readable by the raw converters that are to come.