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From: curt3028@oce.orst.edu (Curt Vandetta)
Newsgroups: comp.databases
Subject: More on image databases
Message-ID: <15498@orstcs.CS.ORST.EDU>
Date: 5 Feb 90 18:47:38 GMT
Sender: usenet@orstcs.CS.ORST.EDU
Reply-To: curt3028@oce.orst.edu (Curt Vandetta)
Organization: College of Oceanography, Oregon State Univ., Corvallis, Or.
Lines: 61


  Hello Folks,

  I've been reading the discussion here about an image database
  and I'm quite interested in this myself.  I'm working for a 
  professor who is doing satellite image processing, and I've 
  put together a database to keep track of his images.  I've found
  that the relational model works very well for keep track of 
  the properties of each image, like which satellite the image was
  taken from, where the raw data is, which algorithms were used to
  process the image, etc.  But I have not been able to put the images
  themselves into the database, only the path to the image (this is all
  being done on a UNIX system so the path is like /img1/1982/...).
  The problem is that I have a byte stream that is 262.144K (the images
  are 512 x 512 x 8bits, some day to be 24bits deep) which is much to
  big for a single column, and a head ache to try to maintain multiple
  columns (like 512 columns one for each raster line).  

  The idea of compressing the image before I store it brings me to the
  problem of variable length columns (not every image will compress
  to the same size) and my still be to large for one column. Plus,
  I lose the ability (or at least possibility) of doing queries on
  the image itself.  (See below for a further explanation)

  I'm more than convinced that I will need to migrate to an object
  oriented model to keep the images in the database themselves, and 
  I'm in the process of coming to speed on the object oriented approach.
  So please for give me if this next question is obvious, but what I
  hope to do (someday), is have the database setup in such a way that
  the end-user can do querys on say, pixel values inside of an image.
  Before you say "Why would you want to do that!?", let me explain.
  Each of the images are of piece of the coastline (refered to as tiles)
  from Washington to California, that's on the Pacific Ocean for those
  who aren't good at geography :-) and each image measures ocean
  surface temperature.  So what I have are tiles (512 x 512 and 8 bits
  deep) representing the temperature of the ocean.  Now what some
  Oceanographer is going to want to do with this database is make a 
  query like "Give me all of the tiles e (where e is say the tile that
  has the San Francisco Bay in it) where the average temperature for the
  bay is above 55 degrees"  Don't let the "average part" confuse the
  issue here, that was just an example, the query could be on say
  pixel 10245, so it would "every tile with pixel 10245 greater than
  134 (a byte value that represents 55 degrees)".

  Now before I spend years on the object oriented model, is this
  kind of thing even possible under the object oriented or even
  relation model?  The type of query requires that each byte value
  (or pixel value for the graphics people) be maintain and searchable
  by the database.

  And all of this doesn't even bring be to issue of viewing each image,
  but that's a topic for another news group :-)

  Anyway, what I was hoping to get from this posting was the names of
  some people who are doing similar work, it would sure be nice to hear
  how others have approached this problem (or would approach, I certainly
  don't want to keep others from responding!)

  Thanks for hearing me out,
  Curt
  curt@oce.orst.edu