Digital photography RAW files
on the web:
OpenRAW.org - documentation of RAW file formats
http://www.luminous-landscape.com/tutorials/jpg-follies.shtml - some examples of why RAW is better than jpeg
should you convert RAW files to DNG format:
an example of use of the RAW file - post-processing to regain highlight information as was done with the image on the right, whereas the image on the left is straight jpeg from the Olympus E510.
digital photography RAW files are the files that most cameras can output and allow to be saved on your memory card or computer which contain the raw digital data derived from the sensor with usually no image processing performed on the file but with added metadata stored within the file relating to the camera used, time, date, settings used (such as white balance, shutter, aperture, ISO) and in some cameras, GPS location data.
you cannot view the image of a RAW file without it first being processed by a RAW converter software.
unfortunately each camera manufacturer has its own proprietary formatting of the RAW file and this changes with each model they put out which usually means when you buy a new camera, you will need to update your RAW converter software (fortunately, when you buy the camera it usually comes with the manufacturer's version of RAW conversion software included to get you started).
RAW files tend to be quite large (10-20Mb is common for 10 mpixel cameras), although some manufacturers have smaller files due to lossless compression of the RAW files.
advantages of RAW files:
altering white balance is significantly easier and as it is in 12-14bit space rather than jpeg's 8 bit space gives better results.
the 12bit or 14bit data space of RAW files allows each pixel to have 4,096 or 16,384 brightness levels instead of only 256 as in a 8 bit jpg
this means MUCH better images IF you are going to do significant post-processing which may cause excessive posterisation effect if using only 8 bit data (you can see this in the final histogram as being jagged points instead of smooth curves)
RAW files hold more highlight data and thus allow errors in exposure to be more readily corrected as well has high contrast scenes better able to be post-processed. Thus blown highlights can be corrected more effectively although perhaps not completely.
as it holds all the RAW data, even better quality images may be obtainable in the future as RAW conversion software improves.
some manufacturers allow an alternative smaller RAW file which converts into a lower resolution image than the full RAW file (eg. Canon's "sRAW" file - although this is of dubious benefit but may be useful for action photographers who want to post-process their rapid burst images and are not so concerned with image resolution.
as an attempt at creating a generic RAW file format which hopefully will be more likely to be accessible in the future, Adobe have created their RAW file format called DNG, so many users convert their original proprietary RAW files to DNG format.
each manufacturer tends to use their own file extension name for their RAW files:
Adobe: .dng - also can be created in camera by Pentax K10D, Leica M8, Hasselblad H2D, Samsung pro 815.
RAW file processing software:
A brief list of earliest version of PC software that supports some popular camera models:
NB. disclaimer - the information below may not be exact, please double check with software provider.
|Camera||Adobe Photoshop||Adobe Lightroom||Phase One|
|C8080WZ||CS or RSE||v1.0|
|1D Mark IIN||v1.0|
|1D Mark III||CS3 ACR4.1||v1.1||n/a|
|S5 Pro||CS3 ACR4.1||v1.1|