John, This is the only page I can find that sort of explains the "file offset" http://www.ee.cooper.edu/courses/course_pages/past_courses/EE458/TIFF/ It takes forever to load.
Here are some of the places it is mentioned in the page. " If value can fit into Value Offset field, it will be placed there. It value cannot fit, Value Offset will contain a pointer (file offset from file beginning) to where value is located." "The DE "length" (sometimes called the "count") field contains the number of items of the specified data type provided. It is specified in terms of the data type, not the total number of bytes required for storage. A single SHORT tag (data type 3) has a length of one and not two, for example. The final field in a DE is the "value offset" field. This field usually contains the file offset to the actual data associated with the tag. In other words, the data associated with a DE does not have to be physically stored with the DE but can reside anywhere in the TIFF file. Again, data pointers must be followed to find the actual data. If the data associated with a DE is four bytes or less in length, it can be stored in the "value offset" field directly instead of at a location pointed to by the this field. This was done to increase TIFF performance when retrieving small data items. Any data stored in "value offset" must be left justified (stored toward the lower-numbered bytes). The "type" and "length" fields must be consulted to determine if the total amount of storage required by a data item is four or fewer bytes and therefore whether it can be stored directly in the "value offset" field." I had a few moments to spare and figured I'd try to help with something I have no clue about. If this is of no help at all, just ignore this email. On Thu, 22 Jul 2004 08:29:07 -0700 (PDT), John Hebert <[EMAIL PROTECTED]> wrote: > Howdy, > > I am trying to understand the TIFF file format and I > came across a term: "file off-set". I kinda have an > idea what this is, but I am not sure. > > I think it referring to a position in the file where > actual image data starts, so that a header section can > exist to provide meta-data about the image. (?) > > Can anyone define what a file off-set is or point me > to a good explanation? > > Thanks, > John > > __________________________________ > Do you Yahoo!? > Vote for the stars of Yahoo!'s next ad campaign! > http://advision.webevents.yahoo.com/yahoo/votelifeengine/ > > _______________________________________________ > General mailing list > [email protected] > http://brlug.net/mailman/listinfo/general_brlug.net > -- Adam Melancon Work: http://www.vermilion.lib.la.us Personal: http://www.melancon.org
