On 2005-09-14 05:52, Godfrey DiGiorgi wrote: > A RAW format image file is generally an enclosure file that contains > the following: > - Camera metadata: all the parameter for JPEG conversion that would > have been used in-camera for JPEG format image files plus bits like > time/date/manufacturer private data/etc.
such as the camera's serial number I guess this could include - sensor faults (defective, calibration) - image info (lense model, aperture, time, focal length, distance) I guess it should be a simple task to build a poor lense with strong vignetting or strong distortions - and compensate most of these flaws by software later on? This would require some kind of reasonable characterisation how to compensate those flaws. I guess part of it is the reasons for proprietary raw formats. http://openraw.org/faq/?id=14 does not show that many infos about What is metadata and what is it good for? I don't know how much of this error correcting options are used now and will be used in the future. But I wonder how big this portion of raw info is, the more detailed it becomes. > - typically a JPEG thumbnail and JPEG preview rendering at low > resolution (maybe more) > - sensor data either uncompressed or losslessly compressed, a simple > 2D matrix > > Is there some kind of 'golden raw' which may be used by the processing > > software in order to compensate known errors? If it's not > > preprocessed into > > the raw output, is it included within every raw file? > > Some of the parameters are constants fixed by the manufacturer for a > particular camera and built into the RAW converter at compile/link > time (that's why RAW conversion software usually needs to be revised > to accommodate new camera models), the rest are supplied in the > camera metadata. > > There are two RAW standards efforts going on to normalize and > regularize the representation of RAW camera data: Adobe's Digital > Negative specification and the OpenRAW effort. Both of these propose > a standardized enclosure format and a way of representing metadata/ > processing parameters such that a generic RAW conversion algorithm > can be devised independent of camera specific software development. > They are both still young efforts. I wonder whether they are sufficient for all the manufacturer's needs. The current abuse of EXIF "maker notes" is a sign that either the standard is not suited very well, or manufacturers don't mind the standards. - Martin
