CLIM mail archive


Image Processing in CLIM

We are thinking about porting OBVIUS (Object-Based Vision and Image
Understanding System) to CLIM.  In order to do this we need precise
control over color rendering.  It isn't clear in the CLIM 1.0
document whether CLIM supports the functionality we need.  Here is
what we need.  

8-Bit Color Systems: We need to have enough control over the color
table such that when we ask for a color, we either get it or get a
condition.  What we need to avoid is asking for a particular color and
then getting the closest color already in the color table.  What sort
of support is there for this situation?  It seems that

  (clim:draw-design (clim:make-pattern array colors) medium) ; p154

would work ok if (A) it were implemented (p154 says that this
technique is not supported in the present implementation) and (B) it
would use the colors you ask for and not closest approximations
already in color-map.  Is this implemented?  If not, when or what
other support is there for drawing 8-bit images?  Also I'm concerned
about efficiency here, it appears that this might be inefficient to
have to load the color-map each time draw-design is called.

24-Bit Color Systems: We need to be able to draw 24-bit images using
either a 2d array of 8-bit values for grey-scale images, or three 2d
arrays of 8-bit values for color images.  The draw-design is obviously
unsuitable for 24-bit operations, since a large image could
potentially have as many colors as pixels.  Also, it isn't immediately
obvious how to manipulate 24-bit images.  It appears that a better
approach would allow the user to specify color operations using three
2d arrays of real values.  Please tell me what the thinking is for
24-bit images and what support is available for them in CLIM 1.0.

-- jonathan


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