Zbob:   
      
   I do NOT work with Hubble images, but rather with images taken of the   
   surface of the Earth by Earth-orbiting satellites.  However, I have   
   kicked around a lot of digital images, enhancing them so that the subtle   
   information within the digital data can be made obvious.  This is what   
   is done in "remote sensing."   
      
   >From my experience, I assume that Hubble images are "enhanced" for the   
   following reasons:   
      
   --1-- in each spectral band, the number of grey levels used by the data   
   are too few to show details to the rather insensitive human eye.  Thus   
   the data are "stretched" over a larger range of data numbers, e.g., from   
   an original 35-42 to a resulting 0-128.   
      
   --2-- A series of "grey-level" images, each from a "band" in the em   
   spectrum, are not very informative.  Since we humans see color, contrast   
   enhanced grey-scale data can be projected onto a color monitor (or color   
   film) with:   
      
   --2a-- a different color assignment for each data number.  The resulting   
   color image is a "pseudocolor" image.   
      
   --2b-- a different color filter for each selected band.  If the red band   
   is projected through a red filter, green through green, and blue through   
   blue, then the result is a "natural color" image.  If an infrared band   
   (light which we can not see) is projected through a red filter, red   
   through a green filter and green through a blue filter, then the result   
   is a "false color" image.   
      
   Different astronomy sensors can look at very different parts of the em   
   spectrum.  Sensors can record such items as the distribution of iron   
   atoms, hydrogen ions, stellar surface temperatures, etc. Thus, the data   
   can be shown only when contrast enhanced and colorized.  Computers do   
   not need this, but people do.   
      
      
   Fred   
      
   Zbob wrote:   
      
   > I saw a story on the news that there is a "Watergate of space science   
   > going on" in that graphics artists are colorizing the images from   
   > Hubble to make them more pleasing to the public.  Can anyone confirm   
   > that story?  I would think with spectral data, the colors would be   
   > known and no need to make them up.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)